Merge branch 'transformer_refactoring_from_pretrain_refactoring' into 'master'

Major refactoring, combining gpt2 and bert

See merge request ADLR/megatron-lm!8

docker/Dockerfile

 # ===========
 # base images
 # ===========
-FROM nvcr.io/nvidia/pytorch:19.05-py3
+FROM nvcr.io/nvidia/pytorch:19.09-py3
 
 
 # ===============
@@ -27,12 +27,3 @@ RUN pip install --upgrade pip && \
 COPY requirements.txt /tmp/
 RUN pip install --upgrade --ignore-installed -r /tmp/requirements.txt
 
-
-# ===========
-# latest apex
-# ===========
-RUN pip uninstall -y apex && \
-git clone https://github.com/NVIDIA/apex.git ~/apex && \
-cd ~/apex && \
-pip install -v --no-cache-dir --global-option="--cpp_ext" --global-option="--cuda_ext" .
-

docker/README.md

-Note that as of now you need to have PySOL cloned to the directory here before building the container.

evaluate_gpt2.py

@@ -29,7 +29,6 @@ from megatron.fp16 import FP16_Module
 from megatron.fp16 import FP16_Optimizer
 from megatron.learning_rates import AnnealingLR
 from megatron.model import GPT2Model
-from megatron.model import gpt2_get_params_for_weight_decay_optimization
 from megatron.model import DistributedDataParallel as DDP
 from megatron import mpu
 from apex.optimizers import FusedAdam as Adam

generate_samples.py

@@ -26,9 +26,8 @@ import argparse
 import time
 from arguments import get_args
 from megatron.utils import Timers
-from pretrain_gpt2 import initialize_distributed
-from pretrain_gpt2 import set_random_seed
-from pretrain_gpt2 import get_train_val_test_data
+from megatron.utils import initialize_distributed
+from megatron.utils import set_random_seed
 from pretrain_gpt2 import get_masks_and_position_ids
 from megatron.utils import load_checkpoint
 from megatron.data_utils import make_tokenizer
@@ -96,7 +95,8 @@ def get_batch(context_tokens, args):
         tokens,
         args.eod_token,
         args.reset_position_ids,
-        args.reset_attention_mask)
+        args.reset_attention_mask,
+        False)
 
     return tokens, attention_mask, position_ids
 
@@ -361,7 +361,7 @@ def switch(val1, val2, boolean):
     boolean = boolean.type_as(val1)
     return (1-boolean)*val1 + boolean*val2
 
-def sample_sequence_batch(model, context_tokens, context_lengths, attention_mask, position_ids, tokenizer, args, maxlen=None):
+def sample_sequence_batch(model, context_tokens, context_lengths, attention_mask, position_ids, tokenizer, args, maxlen=None, type_ids=None):
     model.eval()
     with torch.no_grad():
         context_length = context_lengths.min().item()
@@ -384,16 +384,21 @@ def sample_sequence_batch(model, context_tokens, context_lengths, attention_mask
         while context_length <= (maxlen):
 
             if args.recompute:
-                logits = model(tokens, position_ids, attention_mask)
+                logits = model(tokens, position_ids, attention_mask, tokentype_ids=type_ids)
                 logits = logits[:, context_length - 1, :]
             else:
+                types2use = None
                 if counter == 0:
                     tokens2use = tokens[:, :context_length]
                     positions2use = position_ids[:, :context_length]
+                    if type_ids is not None:
+                        types2use = type_ids[:, :context_length]
                 else:
                     tokens2use = tokens[:, context_length - 1].view(batch_size, -1)
                     positions2use = position_ids[:, context_length - 1].view(batch_size, -1)
-                logits, layer_past = model(tokens2use, positions2use, attention_mask, layer_past=layer_past, get_present=True)
+                    if type_ids is not None:
+                        types2use = type_ids[:, context_length - 1].view(batch_size, -1)
+                logits, layer_past = model(tokens2use, positions2use, attention_mask, layer_past=layer_past, get_key_value=True, tokentype_ids=types2use)
                 logits = logits[:, -1].view(batch_size,-1).contiguous()
 
             if args.greedy:

megatron/fp16/fp16.py

@@ -22,6 +22,9 @@ from torch._utils import _flatten_dense_tensors, _unflatten_dense_tensors
 from .loss_scaler import DynamicLossScaler, LossScaler
 from .fp16util import model_grads_to_master_grads, master_params_to_model_params, clip_grad_norm
 
+
+from megatron.module import MegatronModule
+
 FLOAT_TYPES = (torch.FloatTensor, torch.cuda.FloatTensor)
 HALF_TYPES = (torch.HalfTensor, torch.cuda.HalfTensor)
 
@@ -56,7 +59,7 @@ def fp16_to_fp32(val):
         return val
     return conversion_helper(val, float_conversion)
 
-class FP16_Module(nn.Module):
+class FP16_Module(MegatronModule):
     def __init__(self, module):
         super(FP16_Module, self).__init__()
         self.add_module('module', module.half())
@@ -67,6 +70,11 @@ class FP16_Module(nn.Module):
     def state_dict(self, destination=None, prefix='', keep_vars=False):
         return self.module.state_dict(destination, prefix, keep_vars)
 
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        return self.module.state_dict_for_save_checkpoint(destination, prefix,
+                                                          keep_vars)
+
     def load_state_dict(self, state_dict, strict=True):
         self.module.load_state_dict(state_dict, strict=strict)
 

megatron/model/__init__.py

@@ -14,7 +14,6 @@
 # limitations under the License.
 
 from .distributed import *
-from .gpt2_modeling import gpt2_get_params_for_weight_decay_optimization
-from .gpt2_modeling import GPT2Model
-from .model import BertModel
-from .model import get_params_for_weight_decay_optimization
+from .bert_model import BertModel
+from .gpt2_model import GPT2Model
+from .utils import get_params_for_weight_decay_optimization

megatron/model/bert_model.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""BERT model."""
+
+import torch
+
+from megatron.module import MegatronModule
+
+from .language_model import parallel_lm_logits
+from .language_model import get_language_model
+from .transformer import LayerNorm
+from .utils import gelu
+from .utils import get_linear_layer
+from .utils import init_method_normal
+from .utils import scaled_init_method_normal
+
+
+def bert_attention_mask_func(attention_scores, attention_mask):
+    attention_scores = attention_scores + attention_mask
+    return attention_scores
+
+
+def bert_extended_attention_mask(attention_mask, dtype):
+    # We create a 3D attention mask from a 2D tensor mask.
+    # [b, 1, s]
+    attention_mask_b1s = attention_mask.unsqueeze(1)
+    # [b, s, 1]
+    attention_mask_bs1 = attention_mask.unsqueeze(2)
+    # [b, s, s]
+    attention_mask_bss = attention_mask_b1s * attention_mask_bs1
+    # [b, 1, s, s]
+    extended_attention_mask = attention_mask_bss.unsqueeze(1)
+    # Since attention_mask is 1.0 for positions we want to attend and 0.0
+    # for masked positions, this operation will create a tensor which is
+    # 0.0 for positions we want to attend and -10000.0 for masked positions.
+    # Since we are adding it to the raw scores before the softmax, this is
+    # effectively the same as removing these entirely.
+    # fp16 compatibility
+    extended_attention_mask = extended_attention_mask.to(dtype=dtype)
+    extended_attention_mask = (1.0 - extended_attention_mask) * -10000.0
+
+    return extended_attention_mask
+
+
+def bert_position_ids(token_ids):
+    # Create position ids
+    seq_length = token_ids.size(1)
+    position_ids = torch.arange(seq_length, dtype=torch.long,
+                                device=token_ids.device)
+    position_ids = position_ids.unsqueeze(0).expand_as(token_ids)
+
+    return position_ids
+
+
+
+class BertLMHead(MegatronModule):
+    """Masked LM head for Bert
+
+    Arguments:
+        mpu_vocab_size: model parallel size of vocabulary.
+        hidden_size: hidden size
+        init_method: init method for weight initialization
+        layernorm_epsilon: tolerance for layer norm divisions
+        parallel_output: wether output logits being distributed or not.
+    """
+    def __init__(self, mpu_vocab_size, hidden_size, init_method,
+                 layernorm_epsilon, parallel_output):
+
+        super(BertLMHead, self).__init__()
+
+        self.bias = torch.nn.Parameter(torch.zeros(mpu_vocab_size))
+        self.bias.model_parallel = True
+        self.parallel_output = parallel_output
+
+        self.dense = get_linear_layer(hidden_size, hidden_size, init_method)
+        self.layernorm = LayerNorm(hidden_size, eps=layernorm_epsilon)
+
+
+    def forward(self, hidden_states, word_embeddings_weight):
+        hidden_states = self.dense(hidden_states)
+        hidden_states = gelu(hidden_states)
+        hidden_states = self.layernorm(hidden_states)
+        output = parallel_lm_logits(hidden_states,
+                                    word_embeddings_weight,
+                                    self.parallel_output,
+                                    bias=self.bias)
+        return output
+
+
+
+class BertModel(MegatronModule):
+    """Bert Language model."""
+
+    def __init__(self,
+                 num_layers,
+                 vocab_size,
+                 hidden_size,
+                 num_attention_heads,
+                 embedding_dropout_prob,
+                 attention_dropout_prob,
+                 output_dropout_prob,
+                 max_sequence_length,
+                 checkpoint_activations,
+                 checkpoint_num_layers=1,
+                 add_binary_head=False,
+                 layernorm_epsilon=1.0e-5,
+                 init_method_std=0.02,
+                 num_tokentypes=0,
+                 parallel_output=True):
+
+        super(BertModel, self).__init__()
+
+        self.add_binary_head = add_binary_head
+        self.parallel_output = parallel_output
+        init_method = init_method_normal(init_method_std)
+
+        self.language_model, self._language_model_key = get_language_model(
+            num_layers=num_layers,
+            vocab_size=vocab_size,
+            hidden_size=hidden_size,
+            num_attention_heads=num_attention_heads,
+            embedding_dropout_prob=embedding_dropout_prob,
+            attention_dropout_prob=attention_dropout_prob,
+            output_dropout_prob=output_dropout_prob,
+            max_sequence_length=max_sequence_length,
+            num_tokentypes=num_tokentypes,
+            add_pooler=self.add_binary_head,
+            attention_mask_func=bert_attention_mask_func,
+            checkpoint_activations=checkpoint_activations,
+            checkpoint_num_layers=checkpoint_num_layers,
+            layernorm_epsilon=layernorm_epsilon,
+            init_method=init_method,
+            scaled_init_method=scaled_init_method_normal(init_method_std,
+                                                         num_layers),
+            residual_connection_post_layernorm=True)
+
+        self.lm_head = BertLMHead(
+            self.language_model.embedding.word_embeddings.weight.size(0),
+            hidden_size, init_method, layernorm_epsilon, parallel_output)
+        self._lm_head_key = 'lm_head'
+
+        if self.add_binary_head:
+            self.binary_head = get_linear_layer(hidden_size, 2, init_method)
+            self._binary_head_key = 'binary_head'
+
+
+    def forward(self, input_ids, attention_mask,
+                tokentype_ids=None):
+
+        extended_attention_mask = bert_extended_attention_mask(
+            attention_mask, next(self.language_model.parameters()).dtype)
+        position_ids = bert_position_ids(input_ids)
+
+        if self.add_binary_head:
+            lm_output, pooled_output = self.language_model(
+                input_ids,
+                position_ids,
+                extended_attention_mask,
+                tokentype_ids=tokentype_ids)
+        else:
+            lm_output = self.language_model(
+                input_ids,
+                position_ids,
+                extended_attention_mask,
+                tokentype_ids=tokentype_ids)
+
+        # Output.
+        lm_logits = self.lm_head(
+            lm_output, self.language_model.embedding.word_embeddings.weight)
+
+        if self.add_binary_head:
+            binary_logits = self.binary_head(pooled_output)
+            return lm_logits, binary_logits
+
+        return lm_logits, None
+
+
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        """For easy load when model is combined with other heads,
+        add an extra key."""
+
+        state_dict_ = {}
+        state_dict_[self._language_model_key] \
+            = self.language_model.state_dict_for_save_checkpoint(
+                destination, prefix, keep_vars)
+        state_dict_[self._lm_head_key] \
+            = self.lm_head.state_dict_for_save_checkpoint(
+                destination, prefix, keep_vars)
+        if self.add_binary_head:
+            state_dict_[self._binary_head_key] \
+                = self.binary_head.state_dict(destination, prefix, keep_vars)
+        return state_dict_
+
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Customized load."""
+
+        self.language_model.load_state_dict(
+            state_dict[self._language_model_key], strict=strict)
+        self.lm_head.load_state_dict(state_dict[self._lm_head_key],
+                                     strict=strict)
+        if self.add_binary_head:
+            self.binary_head.load_state_dict(state_dict[self._binary_head_key],
+                                             strict=strict)

megatron/model/distributed.py

@@ -20,8 +20,10 @@ from torch.nn.modules import Module
 from torch.autograd import Variable
 
 from megatron import mpu
+from megatron.module import MegatronModule
 
-class DistributedDataParallel(Module):
+
+class DistributedDataParallel(MegatronModule):
 
     def __init__(self, module):
         super(DistributedDataParallel, self).__init__()
@@ -86,6 +88,11 @@ class DistributedDataParallel(Module):
 
         return sd
 
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        return self.module.state_dict_for_save_checkpoint(destination, prefix,
+                                                          keep_vars)
+
     def load_state_dict(self, state_dict, strict=True):
         self.module.load_state_dict(state_dict, strict=strict)
 

megatron/model/gpt2_model.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""GPT-2 model."""
+
+import torch
+
+from megatron.module import MegatronModule
+
+from .language_model import parallel_lm_logits
+from .language_model import get_language_model
+from .utils import init_method_normal
+from .utils import scaled_init_method_normal
+
+
+def gpt2_attention_mask_func(attention_scores, ltor_mask):
+    attention_scores = torch.mul(attention_scores, ltor_mask) - \
+                       10000.0 * (1.0 - ltor_mask)
+    return attention_scores
+
+
+class GPT2Model(MegatronModule):
+    """GPT-2 Language model."""
+
+    def __init__(self,
+                 num_layers,
+                 vocab_size,
+                 hidden_size,
+                 num_attention_heads,
+                 embedding_dropout_prob,
+                 attention_dropout_prob,
+                 output_dropout_prob,
+                 max_sequence_length,
+                 checkpoint_activations,
+                 checkpoint_num_layers=1,
+                 layernorm_epsilon=1.0e-5,
+                 init_method_std=0.02,
+                 num_tokentypes=0,
+                 parallel_output=True):
+
+        super(GPT2Model, self).__init__()
+
+        self.parallel_output = parallel_output
+
+        self.language_model, self._language_model_key = get_language_model(
+            num_layers=num_layers,
+            vocab_size=vocab_size,
+            hidden_size=hidden_size,
+            num_attention_heads=num_attention_heads,
+            embedding_dropout_prob=embedding_dropout_prob,
+            attention_dropout_prob=attention_dropout_prob,
+            output_dropout_prob=output_dropout_prob,
+            max_sequence_length=max_sequence_length,
+            num_tokentypes=num_tokentypes,
+            add_pooler=False,
+            attention_mask_func=gpt2_attention_mask_func,
+            checkpoint_activations=checkpoint_activations,
+            checkpoint_num_layers=checkpoint_num_layers,
+            layernorm_epsilon=layernorm_epsilon,
+            init_method=init_method_normal(init_method_std),
+            scaled_init_method=scaled_init_method_normal(init_method_std,
+                                                         num_layers),
+            residual_connection_post_layernorm=False)
+
+
+    def forward(self, input_ids, position_ids, attention_mask,
+                tokentype_ids=None, layer_past=None, get_key_value=False):
+
+        # Language model.
+        lm_output = self.language_model(input_ids,
+                                        position_ids,
+                                        attention_mask,
+                                        tokentype_ids=tokentype_ids,
+                                        layer_past=layer_past,
+                                        get_key_value=get_key_value)
+
+        if get_key_value:
+            lm_output, presents = lm_output
+
+        # Output.
+        output = parallel_lm_logits(
+            lm_output,
+            self.language_model.embedding.word_embeddings.weight,
+            self.parallel_output)
+
+        if get_key_value:
+            output = [output, presents]
+
+        return output
+
+
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+
+        state_dict_ = {}
+        state_dict_[self._language_model_key] \
+            = self.language_model.state_dict_for_save_checkpoint(
+                destination, prefix, keep_vars)
+        return state_dict_
+
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Customized load."""
+
+        if self._language_model_key in state_dict:
+            state_dict = state_dict[self._language_model_key]
+        self.language_model.load_state_dict(state_dict, strict=strict)

megatron/model/gpt2_modeling.py

-# coding=utf-8
-# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""GPT-2 model."""
-
-import torch
-import torch.nn.functional as F
-
-from megatron import mpu
-
-
-def init_method_normal(std=0.02):
-    """Init method based on normal distribution.
-
-    This is only used for embeddings. The transformer has its
-    own initializer.
-    """
-    def init_(tensor):
-        return torch.nn.init.normal_(tensor, mean=0.0, std=std)
-    return init_
-
-
-class GPT2Model(torch.nn.Module):
-    """GPT-2 Language model.
-
-    The output of the forward method are the logits (parallel or
-    serial depending on the `parallel_output` flag.
-    """
-
-    def __init__(self,
-                 num_layers,
-                 vocab_size,
-                 hidden_size,
-                 num_attention_heads,
-                 embedding_dropout_prob,
-                 attention_dropout_prob,
-                 output_dropout_prob,
-                 max_sequence_length,
-                 checkpoint_activations,
-                 checkpoint_num_layers=1,
-                 parallel_output=True):
-
-        super(GPT2Model, self).__init__()
-
-        self.parallel_output = parallel_output
-
-        init_method = init_method_normal(std=0.02)
-
-        # Word embeddings (parallel).
-        self.word_embeddings = mpu.VocabParallelEmbedding(
-            vocab_size, hidden_size, init_method=init_method)
-
-        # Position embedding (serial).
-        self.position_embeddings = torch.nn.Embedding(max_sequence_length,
-                                                      hidden_size)
-
-        # Token type embedding.
-        # Add this as an optional field that can be added through
-        # method call so we can load a pretrain model without
-        # token types and add them as needed.
-        self.tokentype_embeddings = None
-        self.hidden_size = hidden_size
-
-        # Initialize the position embeddings.
-        init_method(self.position_embeddings.weight)
-
-        # Embeddings dropout
-        self.embedding_dropout = torch.nn.Dropout(embedding_dropout_prob)
-
-        # Transformer
-        self.transformer = mpu.GPT2ParallelTransformer(num_layers,
-                                                       hidden_size,
-                                                       num_attention_heads,
-                                                       attention_dropout_prob,
-                                                       output_dropout_prob,
-                                                       checkpoint_activations,
-                                                       checkpoint_num_layers)
-
-
-    def add_tokentype_embeddings(self, num_tokentypes):
-        if self.tokentype_embeddings is not None:
-            raise Exception('tokentype embeddings is already initialized')
-        if torch.distributed.get_rank() == 0:
-            print('adding embedding for {} tokentypes'.format(num_tokentypes),
-                  flush=True)
-        self.tokentype_embeddings = torch.nn.Embedding(num_tokentypes,
-                                                       self.hidden_size)
-
-
-    def forward(self, input_ids, position_ids, attention_mask,
-                layer_past=None, get_present=False, tokentype_ids=None):
-
-        # Embeddings.
-        words_embeddings = self.word_embeddings(input_ids)
-        position_embeddings = self.position_embeddings(position_ids)
-        embeddings = words_embeddings + position_embeddings
-        if tokentype_ids is not None:
-            assert self.tokentype_embeddings is not None
-            embeddings = embeddings + self.tokentype_embeddings(tokentype_ids)
-        else:
-            assert self.tokentype_embeddings is None
-
-        # Dropout.
-        embeddings = self.embedding_dropout(embeddings)
-
-        # Transformer.
-        transformer_output = self.transformer(embeddings, attention_mask,
-                                              layer_past=layer_past,
-                                              get_present=get_present)
-        if get_present:
-            transformer_output, presents = transformer_output
-
-        # Parallel logits.
-        transformer_output_parallel = mpu.copy_to_model_parallel_region(
-            transformer_output)
-        logits_parallel = F.linear(transformer_output_parallel,
-                                   self.word_embeddings.weight)
-
-        if self.parallel_output:
-            output = logits_parallel
-        else:
-            output = mpu.gather_from_model_parallel_region(logits_parallel)
-        if get_present:
-            output = [output, presents]
-        return output
-
-
-def gpt2_get_params_for_weight_decay_optimization(module):
-
-    weight_decay_params = {'params': []}
-    no_weight_decay_params = {'params': [], 'weight_decay': 0.0}
-    for module_ in module.modules():
-        if isinstance(module_, (mpu.LayerNorm, torch.nn.LayerNorm)):
-            no_weight_decay_params['params'].extend(
-                [p for p in list(module_._parameters.values())
-                 if p is not None])
-        else:
-            weight_decay_params['params'].extend(
-                [p for n, p in list(module_._parameters.items())
-                 if p is not None and n != 'bias'])
-            no_weight_decay_params['params'].extend(
-                [p for n, p in list(module_._parameters.items())
-                 if p is not None and n == 'bias'])
-
-    return weight_decay_params, no_weight_decay_params

megatron/model/language_model.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Transformer based language model."""
+
+import torch
+import torch.nn.functional as F
+
+from megatron import mpu
+from megatron.module import MegatronModule
+
+from .transformer import ParallelTransformer
+from .transformer import TransformerHyperparameters
+from .utils import gelu
+from .utils import get_linear_layer
+
+
+def parallel_lm_logits(input_, word_embeddings_weight, parallel_output,
+                       bias=None):
+    """LM logits using word embedding weights."""
+    # Parallel logits.
+    input_parallel = mpu.copy_to_model_parallel_region(input_)
+    # Matrix multiply.
+    if bias is None:
+        logits_parallel = F.linear(input_parallel, word_embeddings_weight)
+    else:
+        logits_parallel = F.linear(input_parallel, word_embeddings_weight, bias)
+    # Gather if needed.
+    if parallel_output:
+        return logits_parallel
+    else:
+        return mpu.gather_from_model_parallel_region(logits_parallel)
+
+
+def get_language_model(num_layers,
+                       vocab_size,
+                       hidden_size,
+                       num_attention_heads,
+                       embedding_dropout_prob,
+                       attention_dropout_prob,
+                       output_dropout_prob,
+                       max_sequence_length,
+                       num_tokentypes,
+                       attention_mask_func,
+                       add_pooler,
+                       checkpoint_activations,
+                       checkpoint_num_layers,
+                       layernorm_epsilon,
+                       init_method,
+                       scaled_init_method,
+                       residual_connection_post_layernorm):
+    # Transformer hyperparameters.
+    transformer_hparams = TransformerHyperparameters(
+        hidden_size=hidden_size,
+        num_layers=num_layers,
+        num_attention_heads=num_attention_heads,
+        attention_dropout_prob=attention_dropout_prob,
+        output_dropout_prob=output_dropout_prob,
+        mlp_activation_func=gelu,
+        layernorm_epsilon=layernorm_epsilon,
+        init_method=init_method,
+        output_layer_init_method=scaled_init_method,
+        checkpoint_activations=checkpoint_activations,
+        checkpoint_num_layers=checkpoint_num_layers,
+        apply_residual_connection_post_layernorm=residual_connection_post_layernorm)
+    # Language model.
+    language_model = TransformerLanguageModel(
+        transformer_hparams=transformer_hparams,
+        attention_mask_func=attention_mask_func,
+        vocab_size=vocab_size,
+        max_sequence_length=max_sequence_length,
+        embedding_dropout_prob=embedding_dropout_prob,
+        num_tokentypes=num_tokentypes,
+        add_pooler=add_pooler)
+    # key used for checkpoints.
+    language_model_key = 'language_model'
+
+    return language_model, language_model_key
+
+
+
+class Pooler(MegatronModule):
+    """Pooler layer.
+
+    Pool hidden states of a specific token (for example start of the
+    sequence) and add a linear transformation followed by a tanh.
+
+    Arguments:
+        hidden_size: hidden size
+        init_method: weight initialization method for the linear layer.
+            bias is set to zero.
+    """
+    def __init__(self, hidden_size, init_method):
+        super(Pooler, self).__init__()
+        self.dense = get_linear_layer(hidden_size, hidden_size, init_method)
+
+
+    def forward(self, hidden_states, sequence_index=0):
+        # hidden_states: [b, s, h]
+        # sequence_index: index of the token to pool.
+        pooled = hidden_states[:, sequence_index, :]
+        pooled = self.dense(pooled)
+        pooled = torch.tanh(pooled)
+        return pooled
+
+
+class Embedding(MegatronModule):
+    """Language model embeddings.
+
+    Arguments:
+        hidden_size: hidden size
+        vocab_size: vocabulary size
+        max_sequence_length: maximum size of sequence. This
+                             is used for positional embedding
+        embedding_dropout_prob: dropout probability for embeddings
+        init_method: weight initialization method
+        num_tokentypes: size of the token-type embeddings. 0 value
+                        will ignore this embedding
+    """
+    def __init__(self,
+                 hidden_size,
+                 vocab_size,
+                 max_sequence_length,
+                 embedding_dropout_prob,
+                 init_method,
+                 num_tokentypes=0):
+        super(Embedding, self).__init__()
+
+        self.hidden_size = hidden_size
+        self.init_method = init_method
+        self.num_tokentypes = num_tokentypes
+
+        # Word embeddings (parallel).
+        self.word_embeddings = mpu.VocabParallelEmbedding(
+            vocab_size, self.hidden_size, init_method=self.init_method)
+        self._word_embeddings_key = 'word_embeddings'
+
+        # Position embedding (serial).
+        self.position_embeddings = torch.nn.Embedding(
+            max_sequence_length, self.hidden_size)
+        self._position_embeddings_key = 'position_embeddings'
+        # Initialize the position embeddings.
+        self.init_method(self.position_embeddings.weight)
+
+        # Token type embedding.
+        # Add this as an optional field that can be added through
+        # method call so we can load a pretrain model without
+        # token types and add them as needed.
+        self._tokentype_embeddings_key = 'tokentype_embeddings'
+        if self.num_tokentypes > 0:
+            self.tokentype_embeddings = torch.nn.Embedding(self.num_tokentypes,
+                                                           self.hidden_size)
+            # Initialize the token-type embeddings.
+            self.init_method(self.tokentype_embeddings.weight)
+        else:
+            self.tokentype_embeddings = None
+
+        # Embeddings dropout
+        self.embedding_dropout = torch.nn.Dropout(embedding_dropout_prob)
+
+
+    def add_tokentype_embeddings(self, num_tokentypes):
+        """Add token-type embedding. This function is provided so we can add
+        token-type embeddings in case the pretrained model does not have it.
+        This allows us to load the model normally and then add this embedding.
+        """
+        if self.tokentype_embeddings is not None:
+            raise Exception('tokentype embeddings is already initialized')
+        if torch.distributed.get_rank() == 0:
+            print('adding embedding for {} tokentypes'.format(num_tokentypes),
+                  flush=True)
+        self.num_tokentypes = num_tokentypes
+        self.tokentype_embeddings = torch.nn.Embedding(num_tokentypes,
+                                                       self.hidden_size)
+        # Initialize the token-type embeddings.
+        self.init_method(self.tokentype_embeddings.weight)
+
+
+    def forward(self, input_ids, position_ids, tokentype_ids=None):
+        # Embeddings.
+        words_embeddings = self.word_embeddings(input_ids)
+        position_embeddings = self.position_embeddings(position_ids)
+        embeddings = words_embeddings + position_embeddings
+        if tokentype_ids is not None:
+            assert self.tokentype_embeddings is not None
+            embeddings = embeddings + self.tokentype_embeddings(tokentype_ids)
+        else:
+            assert self.tokentype_embeddings is None
+
+        # Dropout.
+        embeddings = self.embedding_dropout(embeddings)
+
+        return embeddings
+
+
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        """For easy load."""
+
+        state_dict_ = {}
+        state_dict_[self._word_embeddings_key] \
+            = self.word_embeddings.state_dict(destination, prefix, keep_vars)
+        state_dict_[self._position_embeddings_key] \
+            = self.position_embeddings.state_dict(
+                destination, prefix, keep_vars)
+        if self.num_tokentypes > 0:
+            state_dict_[self._tokentype_embeddings_key] \
+                = self.tokentype_embeddings.state_dict(
+                    destination, prefix, keep_vars)
+
+        return state_dict_
+
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Customized load."""
+
+        # Word embedding.
+        if self._word_embeddings_key in state_dict:
+            state_dict_ = state_dict[self._word_embeddings_key]
+        else:
+            # for backward compatibility.
+            state_dict_ = {}
+            for key in state_dict.keys():
+                if 'word_embeddings' in key:
+                    state_dict_[key.split('word_embeddings.')[1]] \
+                        = state_dict[key]
+        self.word_embeddings.load_state_dict(state_dict_, strict=strict)
+
+        # Position embedding.
+        if self._position_embeddings_key in state_dict:
+            state_dict_ = state_dict[self._position_embeddings_key]
+        else:
+            # for backward compatibility.
+            state_dict_ = {}
+            for key in state_dict.keys():
+                if 'position_embeddings' in key:
+                    state_dict_[key.split('position_embeddings.')[1]] \
+                        = state_dict[key]
+        self.position_embeddings.load_state_dict(state_dict_, strict=strict)
+
+        # Tokentype embedding.
+        if  self.num_tokentypes > 0:
+            state_dict_ = {}
+            if self._tokentype_embeddings_key in state_dict:
+                state_dict_ = state_dict[self._tokentype_embeddings_key]
+            else:
+                # for backward compatibility.
+                for key in state_dict.keys():
+                    if 'tokentype_embeddings' in key:
+                        state_dict_[key.split('tokentype_embeddings.')[1]] \
+                            = state_dict[key]
+            if len(state_dict_.keys()) > 0:
+                self.tokentype_embeddings.load_state_dict(state_dict_,
+                                                          strict=strict)
+            else:
+                print('***WARNING*** expected tokentype embeddings in the '
+                      'checkpoint but could not find it', flush=True)
+
+
+
+class TransformerLanguageModel(MegatronModule):
+    """Transformer language model.
+
+    Arguments:
+        transformer_hparams: transformer hyperparameters
+        attention_mask_func: a function that takes `unmaksed-attention-scores`
+            with size [b, np, s, s] and an `attention-mask` and will apply
+            the masking. The function should return a masked score of the
+            same size [b, np, s, s].
+          masked-attention-scores = attention_mask_func(
+                                     unmaksed-attention-scores, attention-mask)
+        vocab_size: vocabulary size
+        max_sequence_length: maximum size of sequence. This
+                             is used for positional embedding
+        embedding_dropout_prob: dropout probability for embeddings
+        num_tokentypes: size of the token-type embeddings. 0 value
+                        will ignore this embedding
+    """
+    def __init__(self,
+                 transformer_hparams,
+                 attention_mask_func,
+                 vocab_size,
+                 max_sequence_length,
+                 embedding_dropout_prob,
+                 num_tokentypes=0,
+                 add_pooler=False):
+        super(TransformerLanguageModel, self).__init__()
+
+        self.hidden_size = transformer_hparams['hidden_size']
+        self.num_tokentypes = num_tokentypes
+        self.init_method = transformer_hparams['init_method']
+        self.add_pooler = add_pooler
+
+        # Embeddings
+        self.embedding = Embedding(self.hidden_size,
+                                   vocab_size,
+                                   max_sequence_length,
+                                   embedding_dropout_prob,
+                                   self.init_method,
+                                   self.num_tokentypes)
+        self._embedding_key = 'embedding'
+
+        # Transformer
+        self.transformer = ParallelTransformer(
+            transformer_hparams,
+            attention_mask_func)
+        self._transformer_key = 'transformer'
+
+        # Pooler
+        if self.add_pooler:
+            self.pooler = Pooler(self.hidden_size, self.init_method)
+            self._pooler_key = 'pooler'
+
+
+    def forward(self, input_ids, position_ids, attention_mask,
+                tokentype_ids=None, layer_past=None, get_key_value=False,
+                pooling_sequence_index=0):
+
+        # Embeddings.
+        embedding_output = self.embedding(input_ids, position_ids,
+                                          tokentype_ids=tokentype_ids)
+
+        # Transformer.
+        transformer_output = self.transformer(embedding_output,
+                                              attention_mask,
+                                              layer_past=layer_past,
+                                              get_key_value=get_key_value)
+
+        if self.add_pooler:
+            pooled_output = self.pooler(transformer_output,
+                                        pooling_sequence_index)
+            return transformer_output, pooled_output
+
+        return transformer_output
+
+
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        """For easy load."""
+
+        state_dict_ = {}
+        state_dict_[self._embedding_key] \
+            = self.embedding.state_dict_for_save_checkpoint(
+                destination, prefix, keep_vars)
+        state_dict_[self._transformer_key] \
+            = self.transformer.state_dict_for_save_checkpoint(
+                destination, prefix, keep_vars)
+        if self.add_pooler:
+            state_dict_[self._pooler_key] \
+                = self.pooler.state_dict_for_save_checkpoint(
+                    destination, prefix, keep_vars)
+
+        return state_dict_
+
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Customized load."""
+
+        # Embedding.
+        if self._embedding_key in state_dict:
+            state_dict_ = state_dict[self._embedding_key]
+        else:
+            # for backward compatibility.
+            state_dict_ = {}
+            for key in state_dict.keys():
+                if '_embeddings' in key:
+                    state_dict_[key] = state_dict[key]
+        self.embedding.load_state_dict(state_dict_, strict=strict)
+
+        # Transformer.
+        if self._transformer_key in state_dict:
+            state_dict_ = state_dict[self._transformer_key]
+        else:
+            # for backward compatibility.
+            state_dict_ = {}
+            for key in state_dict.keys():
+                if 'transformer.' in key:
+                    state_dict_[key.split('transformer.')[1]] = state_dict[key]
+        self.transformer.load_state_dict(state_dict_, strict=strict)
+
+        # Pooler.
+        if self.add_pooler:
+            assert 'pooler' in state_dict, \
+                'could not find data for pooler in the checkpoint'
+            self.pooler.load_state_dict(state_dict[self._pooler_key],
+                                        strict=strict)

megatron/model/modeling.py

-# coding=utf-8
-# Copyright 2018 The Google AI Language Team Authors and The HugginFace Inc. team.
-# Copyright (c) 2018, NVIDIA CORPORATION.  All rights reserved.
-# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-"""PyTorch BERT model."""
-
-from __future__ import absolute_import, division, print_function, unicode_literals
-
-import os
-import copy
-import json
-import math
-import logging
-import tarfile
-import tempfile
-import shutil
-
-import torch
-from torch import nn
-import torch.nn.functional as F
-from torch.nn import CrossEntropyLoss
-
-#from torch.utils.checkpoint import checkpoint
-
-from megatron.data_utils.file_utils import cached_path
-
-from megatron import mpu
-
-
-def normal_init_method(mean, std):
-    def init_(tensor):
-        return torch.nn.init.normal_(tensor, mean=mean, std=std)
-    return init_
-
-def scaled_init_method(mean, std, num_layers):
-    """Init method based on N(0, sigma/sqrt(2*num_layers)."""
-    std = std / math.sqrt(2.0 * num_layers)
-    def init_(tensor):
-        return torch.nn.init.normal_(tensor, mean=mean, std=std)
-
-    return init_
-
-logger = logging.getLogger(__name__)
-
-PRETRAINED_MODEL_ARCHIVE_MAP = {
-    'bert-base-uncased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-uncased.tar.gz",
-    'bert-large-uncased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-large-uncased.tar.gz",
-    'bert-base-cased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-cased.tar.gz",
-    'bert-large-cased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-large-cased.tar.gz",
-    'bert-base-multilingual-uncased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-multilingual-uncased.tar.gz",
-    'bert-base-multilingual-cased': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-multilingual-cased.tar.gz",
-    'bert-base-chinese': "https://s3.amazonaws.com/models.huggingface.co/bert/bert-base-chinese.tar.gz",
-}
-CONFIG_NAME = 'bert_config.json'
-WEIGHTS_NAME = 'pytorch_model.bin'
-TF_WEIGHTS_NAME = 'model.ckpt'
-
-def load_tf_weights_in_bert(model, tf_checkpoint_path):
-    """ Load tf checkpoints in a pytorch model
-    """
-    try:
-        import re
-        import numpy as np
-        import tensorflow as tf
-    except ImportError:
-        print("Loading a TensorFlow models in PyTorch, requires TensorFlow to be installed. Please see "
-            "https://www.tensorflow.org/install/ for installation instructions.")
-        raise
-    tf_path = os.path.abspath(tf_checkpoint_path)
-    print("Converting TensorFlow checkpoint from {}".format(tf_path))
-    # Load weights from TF model
-    init_vars = tf.train.list_variables(tf_path)
-    names = []
-    arrays = []
-    for name, shape in init_vars:
-        print("Loading TF weight {} with shape {}".format(name, shape))
-        array = tf.train.load_variable(tf_path, name)
-        names.append(name)
-        arrays.append(array)
-
-    for name, array in zip(names, arrays):
-        name = name.split('/')
-        # adam_v and adam_m are variables used in AdamWeightDecayOptimizer to calculated m and v
-        # which are not required for using pretrained model
-        if any(n in ["adam_v", "adam_m"] for n in name):
-            print("Skipping {}".format("/".join(name)))
-            continue
-        pointer = model
-        for m_name in name:
-            if re.fullmatch(r'[A-Za-z]+_\d+', m_name):
-                l = re.split(r'_(\d+)', m_name)
-            else:
-                l = [m_name]
-            if l[0] == 'kernel' or l[0] == 'gamma':
-                pointer = getattr(pointer, 'weight')
-            elif l[0] == 'output_bias' or l[0] == 'beta':
-                pointer = getattr(pointer, 'bias')
-            elif l[0] == 'output_weights':
-                pointer = getattr(pointer, 'weight')
-            else:
-                pointer = getattr(pointer, l[0])
-            if len(l) >= 2:
-                num = int(l[1])
-                pointer = pointer[num]
-        if m_name[-11:] == '_embeddings':
-            pointer = getattr(pointer, 'weight')
-        elif m_name == 'kernel':
-            array = np.transpose(array)
-        try:
-            assert pointer.shape == array.shape
-        except AssertionError as e:
-            e.args += (pointer.shape, array.shape)
-            raise
-        print("Initialize PyTorch weight {}".format(name))
-        pointer.data = torch.from_numpy(array)
-    return model
-
-
-def gelu(x):
-    """Implementation of the gelu activation function.
-        For information: OpenAI GPT's gelu is slightly different (and gives slightly different results):
-        0.5 * x * (1 + torch.tanh(math.sqrt(2 / math.pi) * (x + 0.044715 * torch.pow(x, 3))))
-    """
-    return x * 0.5 * (1.0 + torch.erf(x / math.sqrt(2.0)))
-
-
-def swish(x):
-    return x * torch.sigmoid(x)
-
-
-ACT2FN = {"gelu": gelu, "relu": torch.nn.functional.relu, "swish": swish}
-
-class BertConfig(object):
-    """Configuration class to store the configuration of a `BertModel`.
-    """
-    def __init__(self,
-                 vocab_size_or_config_json_file,
-                 hidden_size=768,
-                 num_hidden_layers=12,
-                 num_attention_heads=12,
-                 intermediate_size=3072,
-                 hidden_act="gelu",
-                 hidden_dropout_prob=0.1,
-                 attention_probs_dropout_prob=0.1,
-                 max_position_embeddings=512,
-                 type_vocab_size=2,
-                 initializer_range=0.02,
-                 deep_init=False,
-                 fp32_layernorm=False,
-                 fp32_embedding=False,
-                 fp32_tokentypes=False,
-                 layernorm_epsilon=1e-12):
-        """Constructs BertConfig.
-
-        Args:
-            vocab_size_or_config_json_file: Vocabulary size of `inputs_ids` in `BertModel`.
-            hidden_size: Size of the encoder layers and the pooler layer.
-            num_hidden_layers: Number of hidden layers in the Transformer encoder.
-            num_attention_heads: Number of attention heads for each attention layer in
-                the Transformer encoder.
-            intermediate_size: The size of the "intermediate" (i.e., feed-forward)
-                layer in the Transformer encoder.
-            hidden_act: The non-linear activation function (function or string) in the
-                encoder and pooler. If string, "gelu", "relu" and "swish" are supported.
-            hidden_dropout_prob: The dropout probabilitiy for all fully connected
-                layers in the embeddings, encoder, and pooler.
-            attention_probs_dropout_prob: The dropout ratio for the attention
-                probabilities.
-            max_position_embeddings: The maximum sequence length that this model might
-                ever be used with. Typically set this to something large just in case
-                (e.g., 512 or 1024 or 2048).
-            type_vocab_size: The vocabulary size of the `token_type_ids` passed into
-                `BertModel`.
-            initializer_range: The sttdev of the truncated_normal_initializer for
-                initializing all weight matrices.
-        """
-        if isinstance(vocab_size_or_config_json_file, str):
-            with open(vocab_size_or_config_json_file, "r", encoding='utf-8') as reader:
-                json_config = json.loads(reader.read())
-            for key, value in json_config.items():
-                self.__dict__[key] = value
-        elif isinstance(vocab_size_or_config_json_file, int):
-            self.vocab_size = vocab_size_or_config_json_file
-            self.hidden_size = hidden_size
-            self.num_hidden_layers = num_hidden_layers
-            self.num_attention_heads = num_attention_heads
-            self.hidden_act = hidden_act
-            self.intermediate_size = intermediate_size
-            self.hidden_dropout_prob = hidden_dropout_prob
-            self.attention_probs_dropout_prob = attention_probs_dropout_prob
-            self.max_position_embeddings = max_position_embeddings
-            self.type_vocab_size = type_vocab_size
-            self.initializer_range = initializer_range
-            self.deep_init = deep_init
-            self.fp32_layernorm = fp32_layernorm
-            self.fp32_embedding = fp32_embedding
-            self.layernorm_epsilon = layernorm_epsilon
-            self.fp32_tokentypes = fp32_tokentypes
-        else:
-            raise ValueError("First argument must be either a vocabulary size (int)"
-                             "or the path to a pretrained model config file (str)")
-
-    @classmethod
-    def from_dict(cls, json_object):
-        """Constructs a `BertConfig` from a Python dictionary of parameters."""
-        config = BertConfig(vocab_size_or_config_json_file=-1)
-        for key, value in json_object.items():
-            config.__dict__[key] = value
-        return config
-
-    @classmethod
-    def from_json_file(cls, json_file):
-        """Constructs a `BertConfig` from a json file of parameters."""
-        with open(json_file, "r", encoding='utf-8') as reader:
-            text = reader.read()
-        return cls.from_dict(json.loads(text))
-
-    def __repr__(self):
-        return str(self.to_json_string())
-
-    def to_dict(self):
-        """Serializes this instance to a Python dictionary."""
-        output = copy.deepcopy(self.__dict__)
-        return output
-
-    def to_json_string(self):
-        """Serializes this instance to a JSON string."""
-        return json.dumps(self.to_dict(), indent=2, sort_keys=True) + "\n"
-
-try:
-    from apex.normalization.fused_layer_norm import FusedLayerNorm as BertLayerNorm
-except ImportError:
-    print("Better speed can be achieved with apex installed from https://www.github.com/nvidia/apex.")
-    class BertLayerNorm(nn.Module):
-        def __init__(self, hidden_size, eps=1e-12):
-            """Construct a layernorm module in the TF style (epsilon inside the square root).
-            """
-            super(BertLayerNorm, self).__init__()
-            self.weight = nn.Parameter(torch.ones(hidden_size))
-            self.bias = nn.Parameter(torch.zeros(hidden_size))
-            self.variance_epsilon = eps
-
-        def forward(self, x):
-            u = x.mean(-1, keepdim=True)
-            s = (x - u).pow(2).mean(-1, keepdim=True)
-            x = (x - u) / torch.sqrt(s + self.variance_epsilon)
-            return self.weight * x + self.bias
-
-class BertEmbeddings(nn.Module):
-    """Construct the embeddings from word, position and token_type embeddings.
-    """
-    def __init__(self, config):
-        super(BertEmbeddings, self).__init__()
-        #self.word_embeddings = nn.Embedding(config.vocab_size, config.hidden_size)
-        self.word_embeddings = mpu.VocabParallelEmbedding(
-            config.vocab_size, config.hidden_size,
-            init_method=normal_init_method(mean=0.0,
-                                           std=config.initializer_range))
-        self.position_embeddings = nn.Embedding(config.max_position_embeddings, config.hidden_size)
-        self.token_type_embeddings = nn.Embedding(config.type_vocab_size, config.hidden_size)
-
-        # self.LayerNorm is not snake-cased to stick with TensorFlow model variable name and be able to load
-        # any TensorFlow checkpoint file
-        self.fp32_layernorm = config.fp32_layernorm
-        self.fp32_embedding = config.fp32_embedding
-        self.fp32_tokentypes = config.fp32_tokentypes
-        self.LayerNorm = BertLayerNorm(config.hidden_size, eps=config.layernorm_epsilon)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-
-    def forward(self, input_ids, token_type_ids=None):
-        seq_length = input_ids.size(1)
-        position_ids = torch.arange(seq_length, dtype=torch.long, device=input_ids.device)
-        position_ids = position_ids.unsqueeze(0).expand_as(input_ids)
-        if token_type_ids is None:
-            token_type_ids = torch.zeros_like(input_ids)
-
-        words_embeddings = self.word_embeddings(input_ids)
-        position_embeddings = self.position_embeddings(position_ids)
-        token_type_embeddings = self.token_type_embeddings(token_type_ids)
-        if not self.fp32_tokentypes:
-
-            embeddings = words_embeddings + position_embeddings + token_type_embeddings
-            if self.fp32_embedding and not self.fp32_layernorm:
-                embeddings = embeddings.half()
-            previous_type = embeddings.type()
-            if self.fp32_layernorm:
-                embeddings = embeddings.float()
-            embeddings = self.LayerNorm(embeddings)
-            if self.fp32_layernorm:
-                if self.fp32_embedding:
-                    embeddings = embeddings.half()
-                else:
-                    embeddings = embeddings.type(previous_type)
-        else:
-            embeddings = words_embeddings.float() + position_embeddings.float() + token_type_embeddings.float()    
-            if self.fp32_tokentypes and not self.fp32_layernorm:
-                embeddings = embeddings.half()
-            previous_type = embeddings.type()
-            if self.fp32_layernorm:
-                embeddings = embeddings.float()
-            embeddings = self.LayerNorm(embeddings)
-            if self.fp32_layernorm:
-                if self.fp32_tokentypes:
-                    embeddings = embeddings.half()
-                else:
-                    embeddings = embeddings.type(previous_type)
-        embeddings = self.dropout(embeddings)
-        return embeddings
-
-
-class BertSelfAttention(nn.Module):
-    def __init__(self, config):
-        super(BertSelfAttention, self).__init__()
-        if config.hidden_size % config.num_attention_heads != 0:
-            raise ValueError(
-                "The hidden size (%d) is not a multiple of the number of attention "
-                "heads (%d)" % (config.hidden_size, config.num_attention_heads))
-        self.num_attention_heads = config.num_attention_heads
-        self.attention_head_size = int(config.hidden_size / config.num_attention_heads)
-        self.all_head_size = self.num_attention_heads * self.attention_head_size
-
-        self.query = nn.Linear(config.hidden_size, self.all_head_size)
-        self.key = nn.Linear(config.hidden_size, self.all_head_size)
-        self.value = nn.Linear(config.hidden_size, self.all_head_size)
-
-        self.dropout = nn.Dropout(config.attention_probs_dropout_prob)
-
-    def transpose_for_scores(self, x):
-        new_x_shape = x.size()[:-1] + (self.num_attention_heads, self.attention_head_size)
-        x = x.view(*new_x_shape)
-        return x.permute(0, 2, 1, 3)
-
-    def forward(self, hidden_states, attention_mask):
-
-        mixed_query_layer = self.query(hidden_states)
-        mixed_key_layer = self.key(hidden_states)
-        mixed_value_layer = self.value(hidden_states)
-
-        query_layer = self.transpose_for_scores(mixed_query_layer)
-        key_layer = self.transpose_for_scores(mixed_key_layer)
-        value_layer = self.transpose_for_scores(mixed_value_layer)
-
-        # Take the dot product between "query" and "key" to get the raw attention scores.
-        attention_scores = torch.matmul(query_layer, key_layer.transpose(-1, -2))
-        attention_scores = attention_scores / math.sqrt(self.attention_head_size)
-        # Apply the attention mask is (precomputed for all layers in BertModel forward() function)
-        attention_scores = attention_scores + attention_mask
-
-        # Normalize the attention scores to probabilities.
-        attention_probs = nn.Softmax(dim=-1)(attention_scores)
-
-        # This is actually dropping out entire tokens to attend to, which might
-        # seem a bit unusual, but is taken from the original Transformer paper.
-        attention_probs = self.dropout(attention_probs)
-        
-        previous_type = attention_probs.type()
-        context_layer = torch.matmul(attention_probs, value_layer)
-        context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
-        new_context_layer_shape = context_layer.size()[:-2] + (self.all_head_size,)
-        context_layer = context_layer.view(*new_context_layer_shape)
-        return context_layer
-
-
-class BertSelfOutput(nn.Module):
-    def __init__(self, config):
-        super(BertSelfOutput, self).__init__()
-        if hasattr(config, 'deep_init') and config.deep_init:
-            init_method = scaled_init_method(mean=0.0,
-                                             std=config.initializer_range,
-                                             num_layers=config.num_hidden_layers)
-        else:
-            init_method = normal_init_method(mean=0.0,
-                                             std=config.initializer_range)
-        self.dense = mpu.RowParallelLinear(
-            input_size=config.hidden_size,
-            output_size=config.hidden_size,
-            bias=True,
-            input_is_parallel=True,
-            stride=1,
-            init_method=init_method)
-        self.fp32_layernorm = config.fp32_layernorm
-        self.LayerNorm = BertLayerNorm(config.hidden_size, eps=config.layernorm_epsilon)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-
-    def forward(self, hidden_states, input_tensor):
-        hidden_states = self.dense(hidden_states)
-        hidden_states = self.dropout(hidden_states)
-        ln_input = hidden_states + input_tensor
-        previous_type = ln_input.type()
-        if self.fp32_layernorm:
-            ln_input = ln_input.float()
-        hidden_states = self.LayerNorm(ln_input)
-        if self.fp32_layernorm:
-            hidden_states = hidden_states.type(previous_type)
-        return hidden_states
-
-
-class BertAttention(nn.Module):
-    def __init__(self, config):
-        super(BertAttention, self).__init__()
-        self.self = mpu.BertParallelSelfAttention(
-            hidden_size=config.hidden_size,
-            num_attention_heads=config.num_attention_heads,
-            dropout_prob=config.attention_probs_dropout_prob,
-            output_parallel=True,
-            init_method=normal_init_method(mean=0.0,
-                                           std=config.initializer_range))
-        self.output = BertSelfOutput(config)
-
-    def forward(self, input_tensor, attention_mask):
-        self_output = self.self(input_tensor, attention_mask)
-        attention_output = self.output(self_output, input_tensor)
-        return attention_output
-
-
-class BertIntermediate(nn.Module):
-    def __init__(self, config):
-        super(BertIntermediate, self).__init__()
-        self.dense = mpu.ColumnParallelLinear(
-            input_size=config.hidden_size,
-            output_size=config.intermediate_size,
-            bias=True,
-            gather_output=False,
-            stride=1,
-            init_method=normal_init_method(mean=0.0,
-                                           std=config.initializer_range))
-        self.intermediate_act_fn = ACT2FN[config.hidden_act] \
-            if isinstance(config.hidden_act, str) else config.hidden_act
-
-    def forward(self, hidden_states):
-        hidden_states = self.dense(hidden_states)
-        hidden_states = self.intermediate_act_fn(hidden_states)
-        return hidden_states
-
-
-class BertOutput(nn.Module):
-    def __init__(self, config):
-        super(BertOutput, self).__init__()
-        if hasattr(config, 'deep_init') and  config.deep_init:
-            init_method = scaled_init_method(mean=0.0,
-                                             std=config.initializer_range,
-                                             num_layers=config.num_hidden_layers)
-        else:
-            init_method = normal_init_method(mean=0.0,
-                                             std=config.initializer_range)
-        self.dense = mpu.RowParallelLinear(
-            input_size=config.intermediate_size,
-            output_size=config.hidden_size,
-            bias=True,
-            input_is_parallel=True,
-            stride=1,
-            init_method=init_method)
-        self.fp32_layernorm = config.fp32_layernorm
-        self.LayerNorm = BertLayerNorm(config.hidden_size, eps=config.layernorm_epsilon)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-
-    def forward(self, hidden_states, input_tensor):
-        hidden_states = self.dense(hidden_states)
-        hidden_states = self.dropout(hidden_states)
-        ln_input = hidden_states + input_tensor
-        previous_type = ln_input.type()
-        if self.fp32_layernorm:
-            ln_input = ln_input.float()
-        hidden_states = self.LayerNorm(ln_input)
-        if self.fp32_layernorm:
-            hidden_states = hidden_states.type(previous_type)
-        return hidden_states
-
-
-class BertLayer(nn.Module):
-    def __init__(self, config):
-        super(BertLayer, self).__init__()
-        self.attention = BertAttention(config)
-        self.intermediate = BertIntermediate(config)
-        self.output = BertOutput(config)
-
-    def forward(self, hidden_states, attention_mask):
-        attention_output = self.attention(hidden_states, attention_mask)
-        intermediate_output = self.intermediate(attention_output)
-        layer_output = self.output(intermediate_output, attention_output)
-        return layer_output
-
-
-class BertEncoder(nn.Module):
-    def __init__(self, config):
-        super(BertEncoder, self).__init__()
-        #layer = BertLayer(config)
-        #self.layer = nn.ModuleList([copy.deepcopy(layer) for _ in range(config.num_hidden_layers)])
-        self.layer = nn.ModuleList([BertLayer(config) for _ in range(config.num_hidden_layers)])
-
-    # def forward(self, hidden_states, attention_mask, output_all_encoded_layers=True):
-    #     all_encoder_layers = []
-    #     for layer_module in self.layer:
-    #         hidden_states = layer_module(hidden_states, attention_mask)
-    #         if output_all_encoded_layers:
-    #             all_encoder_layers.append(hidden_states)
-    #     if not output_all_encoded_layers:
-    #         all_encoder_layers.append(hidden_states)
-    #     return all_encoder_layers
-    def forward(self, hidden_states, attention_mask, output_all_encoded_layers=True, checkpoint_activations=False):
-        all_encoder_layers = []
-        def custom(start, end):
-            def custom_forward(*inputs):
-                layers = self.layer[start:end]
-                x_ = inputs[0]
-                for layer in layers:
-                    x_ = layer(x_, inputs[1])
-                return x_
-            return custom_forward
-
-        if checkpoint_activations:
-            l = 0
-            num_layers = len(self.layer)
-            chunk_length = 1 #math.ceil(math.sqrt(num_layers))
-            while l < num_layers:
-                hidden_states = mpu.checkpoint(custom(l, l+chunk_length), hidden_states, attention_mask*1)
-                l += chunk_length
-            # decoder layers
-        else:
-            for i,layer_module in enumerate(self.layer):
-                hidden_states = layer_module(hidden_states, attention_mask)
-
-                if output_all_encoded_layers:
-                    all_encoder_layers.append(hidden_states)
-
-        if not output_all_encoded_layers or checkpoint_activations:
-            all_encoder_layers.append(hidden_states)
-        return all_encoder_layers
-
-
-class BertPooler(nn.Module):
-    def __init__(self, config):
-        super(BertPooler, self).__init__()
-        self.dense = nn.Linear(config.hidden_size, config.hidden_size)
-        self.activation = nn.Tanh()
-
-    def forward(self, hidden_states):
-        # We "pool" the model by simply taking the hidden state corresponding
-        # to the first token.
-        first_token_tensor = hidden_states[:, 0]
-        pooled_output = self.dense(first_token_tensor)
-        pooled_output = self.activation(pooled_output)
-        return pooled_output
-
-
-class BertPredictionHeadTransform(nn.Module):
-    def __init__(self, config):
-        super(BertPredictionHeadTransform, self).__init__()
-        self.dense = nn.Linear(config.hidden_size, config.hidden_size)
-        self.transform_act_fn = ACT2FN[config.hidden_act] \
-            if isinstance(config.hidden_act, str) else config.hidden_act
-        self.LayerNorm = BertLayerNorm(config.hidden_size, eps=config.layernorm_epsilon)
-        self.fp32_layernorm = config.fp32_layernorm
-
-    def forward(self, hidden_states):
-        hidden_states = self.dense(hidden_states)
-        hidden_states = self.transform_act_fn(hidden_states)
-        previous_type = hidden_states.type()
-        if self.fp32_layernorm:
-            hidden_states = hidden_states.float()
-        hidden_states = self.LayerNorm(hidden_states)
-        if self.fp32_layernorm:
-            hidden_states = hidden_states.type(previous_type)
-        return hidden_states
-
-
-class BertLMPredictionHead(nn.Module):
-    def __init__(self, config, bert_model_embedding_weights):
-        super(BertLMPredictionHead, self).__init__()
-        self.transform = BertPredictionHeadTransform(config)
-
-        # The output weights are the same as the input embeddings, but there is
-        # an output-only bias for each token.
-        #self.decoder = nn.Linear(bert_model_embedding_weights.size(1),
-        #                         bert_model_embedding_weights.size(0),
-        #                         bias=False)
-        self.decoder_weight = bert_model_embedding_weights
-        self.bias = nn.Parameter(torch.zeros(bert_model_embedding_weights.size(0)))
-        self.bias.model_parallel = True
-        self.fp32_embedding = config.fp32_embedding
-        self.fp32_layernorm = config.fp32_layernorm
-        def convert_to_type(tensor):
-            if self.fp32_embedding:
-                return tensor.half()
-            else:
-                return tensor
-        self.type_converter = convert_to_type
-        self.converted = False
-
-    def forward(self, hidden_states):
-        if not self.converted:
-            self.converted = True
-            if self.fp32_embedding:
-                self.transform.half()
-                if self.fp32_layernorm:
-                    self.transform.LayerNorm.float()
-        hidden_states = self.transform(self.type_converter(hidden_states))
-        # hidden_states = self.decoder(hidden_states) + self.bias
-        hidden_states = mpu.copy_to_model_parallel_region(hidden_states)
-        hidden_states = F.linear(self.type_converter(hidden_states),
-                                 self.type_converter(self.decoder_weight),
-                                 self.type_converter(self.bias))
-        return hidden_states
-
-
-class BertOnlyMLMHead(nn.Module):
-    def __init__(self, config, bert_model_embedding_weights):
-        super(BertOnlyMLMHead, self).__init__()
-        self.predictions = BertLMPredictionHead(config, bert_model_embedding_weights)
-
-    def forward(self, sequence_output):
-        prediction_scores = self.predictions(sequence_output)
-        return prediction_scores
-
-
-class BertOnlyNSPHead(nn.Module):
-    def __init__(self, config):
-        super(BertOnlyNSPHead, self).__init__()
-        self.seq_relationship = nn.Linear(config.hidden_size, 2)
-
-    def forward(self, pooled_output):
-        seq_relationship_score = self.seq_relationship(pooled_output)
-        return seq_relationship_score
-
-
-class BertPreTrainingHeads(nn.Module):
-    def __init__(self, config, bert_model_embedding_weights):
-        super(BertPreTrainingHeads, self).__init__()
-        self.predictions = BertLMPredictionHead(config, bert_model_embedding_weights)
-        self.seq_relationship = nn.Linear(config.hidden_size, 2)
-
-    def forward(self, sequence_output, pooled_output):
-        prediction_scores = self.predictions(sequence_output)
-        for p in self.seq_relationship.parameters():
-            if p is None:
-                continue
-            pooled_output = pooled_output.type_as(p)
-        seq_relationship_score = self.seq_relationship(pooled_output)
-        return prediction_scores, seq_relationship_score
-
-
-class PreTrainedBertModel(nn.Module):
-    """ An abstract class to handle weights initialization and
-        a simple interface for dowloading and loading pretrained models.
-    """
-    def __init__(self, config, *inputs, **kwargs):
-        super(PreTrainedBertModel, self).__init__()
-        if not isinstance(config, BertConfig):
-            raise ValueError(
-                "Parameter config in `{}(config)` should be an instance of class `BertConfig`. "
-                "To create a model from a Google pretrained model use "
-                "`model = {}.from_pretrained(PRETRAINED_MODEL_NAME)`".format(
-                    self.__class__.__name__, self.__class__.__name__
-                ))
-        self.config = config
-
-    def init_bert_weights(self, module):
-        """ Initialize the weights.
-        """
-        if isinstance(module, (nn.Linear, nn.Embedding)):
-            # Slightly different from the TF version which uses truncated_normal for initialization
-            # cf https://github.com/pytorch/pytorch/pull/5617
-            module.weight.data.normal_(mean=0.0, std=self.config.initializer_range)
-        elif isinstance(module, BertLayerNorm):
-            module.bias.data.zero_()
-            module.weight.data.fill_(1.0)
-        if isinstance(module, nn.Linear) and module.bias is not None:
-            module.bias.data.zero_()
-
-    @classmethod
-    def from_pretrained(cls, pretrained_model_name, state_dict=None, cache_dir=None,
-                        fp32_layernorm=False, fp32_embedding=False, layernorm_epsilon=1e-12,
-                        fp32_tokentypes=False, *inputs, **kwargs):
-        """
-        Instantiate a PreTrainedBertModel from a pre-trained model file or a pytorch state dict.
-        Download and cache the pre-trained model file if needed.
-
-        Params:
-            pretrained_model_name: either:
-                - a str with the name of a pre-trained model to load selected in the list of:
-                    . `bert-base-uncased`
-                    . `bert-large-uncased`
-                    . `bert-base-cased`
-                    . `bert-large-cased`
-                    . `bert-base-multilingual-uncased`
-                    . `bert-base-multilingual-cased`
-                    . `bert-base-chinese`
-                - a path or url to a pretrained model archive containing:
-                    . `bert_config.json` a configuration file for the model
-                    . `pytorch_model.bin` a PyTorch dump of a BertForPreTraining instance
-            cache_dir: an optional path to a folder in which the pre-trained models will be cached.
-            state_dict: an optional state dictionnary (collections.OrderedDict object) to use instead of Google pre-trained models
-            *inputs, **kwargs: additional input for the specific Bert class
-                (ex: num_labels for BertForSequenceClassification)
-        """
-        if pretrained_model_name in PRETRAINED_MODEL_ARCHIVE_MAP:
-            archive_file = PRETRAINED_MODEL_ARCHIVE_MAP[pretrained_model_name]
-        else:
-            archive_file = pretrained_model_name
-        # redirect to the cache, if necessary
-        try:
-            resolved_archive_file = cached_path(archive_file, cache_dir=cache_dir)
-        except FileNotFoundError:
-            logger.error(
-                "Model name '{}' was not found in model name list ({}). "
-                "We assumed '{}' was a path or url but couldn't find any file "
-                "associated to this path or url.".format(
-                    pretrained_model_name,
-                    ', '.join(PRETRAINED_MODEL_ARCHIVE_MAP.keys()),
-                    archive_file))
-            return None
-        if resolved_archive_file == archive_file:
-            logger.info("loading archive file {}".format(archive_file))
-        else:
-            logger.info("loading archive file {} from cache at {}".format(
-                archive_file, resolved_archive_file))
-        tempdir = None
-        if os.path.isdir(resolved_archive_file):
-            serialization_dir = resolved_archive_file
-        else:
-            # Extract archive to temp dir
-            tempdir = tempfile.mkdtemp()
-            logger.info("extracting archive file {} to temp dir {}".format(
-                resolved_archive_file, tempdir))
-            with tarfile.open(resolved_archive_file, 'r:gz') as archive:
-                archive.extractall(tempdir)
-            serialization_dir = tempdir
-        # Load config
-        config_file = os.path.join(serialization_dir, CONFIG_NAME)
-        config = BertConfig.from_json_file(config_file)
-        config.fp32_layernorm = fp32_layernorm
-        config.fp32_embedding = fp32_embedding
-        config.layernorm_epsilon = layernorm_epsilon
-        config.fp32_tokentypes = fp32_tokentypes
-        logger.info("Model config {}".format(config))
-        # Instantiate model.
-        model = cls(config, *inputs, **kwargs)
-        if state_dict is None:
-            weights_path = os.path.join(serialization_dir, WEIGHTS_NAME)
-            state_dict = torch.load(weights_path)
-
-        old_keys = []
-        new_keys = []
-        for key in state_dict.keys():
-            new_key = None
-            if 'gamma' in key:
-                new_key = key.replace('gamma', 'weight')
-            if 'beta' in key:
-                new_key = key.replace('beta', 'bias')
-            if new_key:
-                old_keys.append(key)
-                new_keys.append(new_key)
-        for old_key, new_key in zip(old_keys, new_keys):
-            state_dict[new_key] = state_dict.pop(old_key)
-
-        missing_keys = []
-        unexpected_keys = []
-        error_msgs = []
-        # copy state_dict so _load_from_state_dict can modify it
-        metadata = getattr(state_dict, '_metadata', None)
-        state_dict = state_dict.copy()
-        if metadata is not None:
-            state_dict._metadata = metadata
-
-        def load(module, prefix=''):
-            local_metadata = {} if metadata is None else metadata.get(prefix[:-1], {})
-            module._load_from_state_dict(
-                state_dict, prefix, local_metadata, True, missing_keys, unexpected_keys, error_msgs)
-            for name, child in module._modules.items():
-                if child is not None:
-                    load(child, prefix + name + '.')
-        load(model, prefix='' if hasattr(model, 'bert') else 'bert.')
-        if len(missing_keys) > 0:
-            logger.info("Weights of {} not initialized from pretrained model: {}".format(
-                model.__class__.__name__, missing_keys))
-        if len(unexpected_keys) > 0:
-            logger.info("Weights from pretrained model not used in {}: {}".format(
-                model.__class__.__name__, unexpected_keys))
-        if tempdir:
-            # Clean up temp dir
-            shutil.rmtree(tempdir)
-        return model
-
-
-class BertModel(PreTrainedBertModel):
-    """BERT model ("Bidirectional Embedding Representations from a Transformer").
-
-    Params:
-        config: a BertConfig class instance with the configuration to build a new model
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `output_all_encoded_layers`: boolean which controls the content of the `encoded_layers` output as described below. Default: `True`.
-
-    Outputs: Tuple of (encoded_layers, pooled_output)
-        `encoded_layers`: controled by `output_all_encoded_layers` argument:
-            - `output_all_encoded_layers=True`: outputs a list of the full sequences of encoded-hidden-states at the end
-                of each attention block (i.e. 12 full sequences for BERT-base, 24 for BERT-large), each
-                encoded-hidden-state is a torch.FloatTensor of size [batch_size, sequence_length, hidden_size],
-            - `output_all_encoded_layers=False`: outputs only the full sequence of hidden-states corresponding
-                to the last attention block of shape [batch_size, sequence_length, hidden_size],
-        `pooled_output`: a torch.FloatTensor of size [batch_size, hidden_size] which is the output of a
-            classifier pretrained on top of the hidden state associated to the first character of the
-            input (`CLF`) to train on the Next-Sentence task (see BERT's paper).
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = modeling.BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    model = modeling.BertModel(config=config)
-    all_encoder_layers, pooled_output = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config):
-        super(BertModel, self).__init__(config)
-        self.embeddings = BertEmbeddings(config)
-        self.encoder = BertEncoder(config)
-        self.pooler = BertPooler(config)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, output_all_encoded_layers=True, checkpoint_activations=False):
-        if attention_mask is None:
-            attention_mask = torch.ones_like(input_ids)
-        if token_type_ids is None:
-            token_type_ids = torch.zeros_like(input_ids)
-
-        # We create a 3D attention mask from a 2D tensor mask.
-        # Sizes are [batch_size, 1, 1, to_seq_length]
-        # So we can broadcast to [batch_size, num_heads, from_seq_length, to_seq_length]
-        # this attention mask is more simple than the triangular masking of causal attention
-        # used in OpenAI GPT, we just need to prepare the broadcast dimension here.
-        extended_attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
-
-        # Since attention_mask is 1.0 for positions we want to attend and 0.0 for
-        # masked positions, this operation will create a tensor which is 0.0 for
-        # positions we want to attend and -10000.0 for masked positions.
-        # Since we are adding it to the raw scores before the softmax, this is
-        # effectively the same as removing these entirely.
-        extended_attention_mask = extended_attention_mask.to(dtype=next(self.encoder.parameters()).dtype) # fp16 compatibility
-        extended_attention_mask = (1.0 - extended_attention_mask) * -10000.0
-
-        embedding_output = self.embeddings(input_ids, token_type_ids)
-        encoded_layers = self.encoder(embedding_output,
-                                      extended_attention_mask,
-                                      output_all_encoded_layers=output_all_encoded_layers,
-                                      checkpoint_activations=checkpoint_activations)
-        sequence_output = encoded_layers[-1]
-        for p in self.pooler.parameters():
-            if p is None:
-                continue
-            sequence_output = sequence_output.type_as(p)
-            break
-        pooled_output = self.pooler(sequence_output)
-        if not output_all_encoded_layers or checkpoint_activations:
-            encoded_layers = encoded_layers[-1]
-        return encoded_layers, pooled_output
-
-
-class BertForPreTraining(PreTrainedBertModel):
-    """BERT model with pre-training heads.
-    This module comprises the BERT model followed by the two pre-training heads:
-        - the masked language modeling head, and
-        - the next sentence classification head.
-
-    Params:
-        config: a BertConfig class instance with the configuration to build a new model.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `masked_lm_labels`: masked language modeling labels: torch.LongTensor of shape [batch_size, sequence_length]
-            with indices selected in [-1, 0, ..., vocab_size]. All labels set to -1 are ignored (masked), the loss
-            is only computed for the labels set in [0, ..., vocab_size]
-        `next_sentence_label`: next sentence classification loss: torch.LongTensor of shape [batch_size]
-            with indices selected in [0, 1].
-            0 => next sentence is the continuation, 1 => next sentence is a random sentence.
-
-    Outputs:
-        if `masked_lm_labels` and `next_sentence_label` are not `None`:
-            Outputs the total_loss which is the sum of the masked language modeling loss and the next
-            sentence classification loss.
-        if `masked_lm_labels` or `next_sentence_label` is `None`:
-            Outputs a tuple comprising
-            - the masked language modeling logits of shape [batch_size, sequence_length, vocab_size], and
-            - the next sentence classification logits of shape [batch_size, 2].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    model = BertForPreTraining(config)
-    masked_lm_logits_scores, seq_relationship_logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config):
-        super(BertForPreTraining, self).__init__(config)
-        self.bert = BertModel(config)
-        self.cls = BertPreTrainingHeads(config, self.bert.embeddings.word_embeddings.weight)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, masked_lm_labels=None, next_sentence_label=None, checkpoint_activations=False):
-        sequence_output, pooled_output = self.bert(input_ids, token_type_ids, attention_mask,
-                                                   output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        prediction_scores, seq_relationship_score = self.cls(sequence_output, pooled_output)
-
-
-        if masked_lm_labels is not None and next_sentence_label is not None:
-            loss_fct = CrossEntropyLoss(ignore_index=-1)
-            masked_lm_loss = loss_fct(prediction_scores.view(-1, self.config.vocab_size).float(), masked_lm_labels.view(-1))
-            next_sentence_loss = loss_fct(seq_relationship_score.view(-1, 2).float(), next_sentence_label.view(-1))
-            total_loss = masked_lm_loss + next_sentence_loss
-            return total_loss
-        else:
-            return prediction_scores, seq_relationship_score
-
-
-class BertForMaskedLM(PreTrainedBertModel):
-    """BERT model with the masked language modeling head.
-    This module comprises the BERT model followed by the masked language modeling head.
-
-    Params:
-        config: a BertConfig class instance with the configuration to build a new model.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `masked_lm_labels`: masked language modeling labels: torch.LongTensor of shape [batch_size, sequence_length]
-            with indices selected in [-1, 0, ..., vocab_size]. All labels set to -1 are ignored (masked), the loss
-            is only computed for the labels set in [0, ..., vocab_size]
-
-    Outputs:
-        if `masked_lm_labels` is  not `None`:
-            Outputs the masked language modeling loss.
-        if `masked_lm_labels` is `None`:
-            Outputs the masked language modeling logits of shape [batch_size, sequence_length, vocab_size].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    model = BertForMaskedLM(config)
-    masked_lm_logits_scores = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config):
-        super(BertForMaskedLM, self).__init__(config)
-        self.bert = BertModel(config)
-        self.cls = BertOnlyMLMHead(config, self.bert.embeddings.word_embeddings.weight)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, masked_lm_labels=None, checkpoint_activations=False):
-        sequence_output, _ = self.bert(input_ids, token_type_ids, attention_mask,
-                                       output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        prediction_scores = self.cls(sequence_output)
-
-        if masked_lm_labels is not None:
-            loss_fct = CrossEntropyLoss(ignore_index=-1)
-            masked_lm_loss = loss_fct(prediction_scores.view(-1, self.config.vocab_size), masked_lm_labels.view(-1))
-            return masked_lm_loss
-        else:
-            return prediction_scores
-
-
-class BertForNextSentencePrediction(PreTrainedBertModel):
-    """BERT model with next sentence prediction head.
-    This module comprises the BERT model followed by the next sentence classification head.
-
-    Params:
-        config: a BertConfig class instance with the configuration to build a new model.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `next_sentence_label`: next sentence classification loss: torch.LongTensor of shape [batch_size]
-            with indices selected in [0, 1].
-            0 => next sentence is the continuation, 1 => next sentence is a random sentence.
-
-    Outputs:
-        if `next_sentence_label` is not `None`:
-            Outputs the total_loss which is the sum of the masked language modeling loss and the next
-            sentence classification loss.
-        if `next_sentence_label` is `None`:
-            Outputs the next sentence classification logits of shape [batch_size, 2].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    model = BertForNextSentencePrediction(config)
-    seq_relationship_logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config):
-        super(BertForNextSentencePrediction, self).__init__(config)
-        self.bert = BertModel(config)
-        self.cls = BertOnlyNSPHead(config)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, next_sentence_label=None, checkpoint_activations=False):
-        _, pooled_output = self.bert(input_ids, token_type_ids, attention_mask,
-                                     output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        seq_relationship_score = self.cls( pooled_output)
-
-        if next_sentence_label is not None:
-            loss_fct = CrossEntropyLoss(ignore_index=-1)
-            next_sentence_loss = loss_fct(seq_relationship_score.view(-1, 2), next_sentence_label.view(-1))
-            return next_sentence_loss
-        else:
-            return seq_relationship_score
-
-
-class BertForSequenceClassification(PreTrainedBertModel):
-    """BERT model for classification.
-    This module is composed of the BERT model with a linear layer on top of
-    the pooled output.
-
-    Params:
-        `config`: a BertConfig class instance with the configuration to build a new model.
-        `num_labels`: the number of classes for the classifier. Default = 2.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `labels`: labels for the classification output: torch.LongTensor of shape [batch_size]
-            with indices selected in [0, ..., num_labels].
-
-    Outputs:
-        if `labels` is not `None`:
-            Outputs the CrossEntropy classification loss of the output with the labels.
-        if `labels` is `None`:
-            Outputs the classification logits of shape [batch_size, num_labels].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    num_labels = 2
-
-    model = BertForSequenceClassification(config, num_labels)
-    logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config, num_labels=2):
-        super(BertForSequenceClassification, self).__init__(config)
-        self.num_labels = num_labels
-        self.bert = BertModel(config)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-        self.classifier = nn.Linear(config.hidden_size, num_labels)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None, checkpoint_activations=False):
-        _, pooled_output = self.bert(input_ids, token_type_ids, attention_mask, output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        pooled_output = self.dropout(pooled_output)
-        logits = self.classifier(pooled_output)
-
-        if labels is not None:
-            loss_fct = CrossEntropyLoss()
-            loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
-            return loss
-        else:
-            return logits
-
-
-class BertForMultipleChoice(PreTrainedBertModel):
-    """BERT model for multiple choice tasks.
-    This module is composed of the BERT model with a linear layer on top of
-    the pooled output.
-
-    Params:
-        `config`: a BertConfig class instance with the configuration to build a new model.
-        `num_choices`: the number of classes for the classifier. Default = 2.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, num_choices, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, num_choices, sequence_length]
-            with the token types indices selected in [0, 1]. Type 0 corresponds to a `sentence A`
-            and type 1 corresponds to a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, num_choices, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `labels`: labels for the classification output: torch.LongTensor of shape [batch_size]
-            with indices selected in [0, ..., num_choices].
-
-    Outputs:
-        if `labels` is not `None`:
-            Outputs the CrossEntropy classification loss of the output with the labels.
-        if `labels` is `None`:
-            Outputs the classification logits of shape [batch_size, num_labels].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[[31, 51, 99], [15, 5, 0]], [[12, 16, 42], [14, 28, 57]]])
-    input_mask = torch.LongTensor([[[1, 1, 1], [1, 1, 0]],[[1,1,0], [1, 0, 0]]])
-    token_type_ids = torch.LongTensor([[[0, 0, 1], [0, 1, 0]],[[0, 1, 1], [0, 0, 1]]])
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    num_choices = 2
-
-    model = BertForMultipleChoice(config, num_choices)
-    logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config, num_choices=2):
-        super(BertForMultipleChoice, self).__init__(config)
-        self.num_choices = num_choices
-        self.bert = BertModel(config)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-        self.classifier = nn.Linear(config.hidden_size, 1)
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None, checkpoint_activations=False):
-        flat_input_ids = input_ids.view(-1, input_ids.size(-1))
-        flat_token_type_ids = token_type_ids.view(-1, token_type_ids.size(-1))
-        flat_attention_mask = attention_mask.view(-1, attention_mask.size(-1))
-        _, pooled_output = self.bert(flat_input_ids, flat_token_type_ids, flat_attention_mask, output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        pooled_output = self.dropout(pooled_output)
-        logits = self.classifier(pooled_output)
-        reshaped_logits = logits.view(-1, self.num_choices)
-
-        if labels is not None:
-            loss_fct = CrossEntropyLoss()
-            loss = loss_fct(reshaped_logits, labels)
-            return loss
-        else:
-            return reshaped_logits
-
-
-class BertForTokenClassification(PreTrainedBertModel):
-    """BERT model for token-level classification.
-    This module is composed of the BERT model with a linear layer on top of
-    the full hidden state of the last layer.
-
-    Params:
-        `config`: a BertConfig class instance with the configuration to build a new model.
-        `num_labels`: the number of classes for the classifier. Default = 2.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `labels`: labels for the classification output: torch.LongTensor of shape [batch_size]
-            with indices selected in [0, ..., num_labels].
-
-    Outputs:
-        if `labels` is not `None`:
-            Outputs the CrossEntropy classification loss of the output with the labels.
-        if `labels` is `None`:
-            Outputs the classification logits of shape [batch_size, sequence_length, num_labels].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    num_labels = 2
-
-    model = BertForTokenClassification(config, num_labels)
-    logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config, num_labels=2):
-        super(BertForTokenClassification, self).__init__(config)
-        self.num_labels = num_labels
-        self.bert = BertModel(config)
-        self.dropout = nn.Dropout(config.hidden_dropout_prob)
-        #self.classifier = nn.Linear(config.hidden_size, num_labels)
-        self.classifier = mpu.RowParallelLinear(
-            input_size=config.hidden_size,
-            output_size=num_labels,
-            bias=True,
-            input_is_parallel=True,
-            stride=1,
-            init_method=normal_init_method(mean=0.0,
-                                           std=config.initializer_range))
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, labels=None, checkpoint_activations=False):
-        sequence_output, _ = self.bert(input_ids, token_type_ids, attention_mask, output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        with mpu.get_cuda_rng_tracker().fork():
-            sequence_output = self.dropout(sequence_output)
-        logits = self.classifier(sequence_output)
-
-        if labels is not None:
-            loss_fct = CrossEntropyLoss()
-            loss = loss_fct(logits.view(-1, self.num_labels), labels.view(-1))
-            return loss
-        else:
-            return logits
-
-
-class BertForQuestionAnswering(PreTrainedBertModel):
-    """BERT model for Question Answering (span extraction).
-    This module is composed of the BERT model with a linear layer on top of
-    the sequence output that computes start_logits and end_logits
-
-    Params:
-        `config`: a BertConfig class instance with the configuration to build a new model.
-
-    Inputs:
-        `input_ids`: a torch.LongTensor of shape [batch_size, sequence_length]
-            with the word token indices in the vocabulary(see the tokens preprocessing logic in the scripts
-            `extract_features.py`, `run_classifier.py` and `run_squad.py`)
-        `token_type_ids`: an optional torch.LongTensor of shape [batch_size, sequence_length] with the token
-            types indices selected in [0, 1]. Type 0 corresponds to a `sentence A` and type 1 corresponds to
-            a `sentence B` token (see BERT paper for more details).
-        `attention_mask`: an optional torch.LongTensor of shape [batch_size, sequence_length] with indices
-            selected in [0, 1]. It's a mask to be used if the input sequence length is smaller than the max
-            input sequence length in the current batch. It's the mask that we typically use for attention when
-            a batch has varying length sentences.
-        `start_positions`: position of the first token for the labeled span: torch.LongTensor of shape [batch_size].
-            Positions are clamped to the length of the sequence and position outside of the sequence are not taken
-            into account for computing the loss.
-        `end_positions`: position of the last token for the labeled span: torch.LongTensor of shape [batch_size].
-            Positions are clamped to the length of the sequence and position outside of the sequence are not taken
-            into account for computing the loss.
-
-    Outputs:
-        if `start_positions` and `end_positions` are not `None`:
-            Outputs the total_loss which is the sum of the CrossEntropy loss for the start and end token positions.
-        if `start_positions` or `end_positions` is `None`:
-            Outputs a tuple of start_logits, end_logits which are the logits respectively for the start and end
-            position tokens of shape [batch_size, sequence_length].
-
-    Example usage:
-    ```python
-    # Already been converted into WordPiece token ids
-    input_ids = torch.LongTensor([[31, 51, 99], [15, 5, 0]])
-    input_mask = torch.LongTensor([[1, 1, 1], [1, 1, 0]])
-    token_type_ids = torch.LongTensor([[0, 0, 1], [0, 1, 0]])
-
-    config = BertConfig(vocab_size_or_config_json_file=32000, hidden_size=768,
-        num_hidden_layers=12, num_attention_heads=12, intermediate_size=3072)
-
-    model = BertForQuestionAnswering(config)
-    start_logits, end_logits = model(input_ids, token_type_ids, input_mask)
-    ```
-    """
-    def __init__(self, config):
-        super(BertForQuestionAnswering, self).__init__(config)
-        self.bert = BertModel(config)
-        # TODO check with Google if it's normal there is no dropout on the token classifier of SQuAD in the TF version
-        # self.dropout = nn.Dropout(config.hidden_dropout_prob)
-        #self.qa_outputs = nn.Linear(config.hidden_size, 2)
-        self.qa_outputs = mpu.RowParallelLinear(
-            input_size=config.hidden_size,
-            output_size=2,
-            bias=True,
-            input_is_parallel=True,
-            stride=1,
-            init_method=normal_init_method(mean=0.0,
-                                           std=config.initializer_range))
-        self.apply(self.init_bert_weights)
-
-    def forward(self, input_ids, token_type_ids=None, attention_mask=None, start_positions=None, end_positions=None, checkpoint_activations=False):
-        sequence_output, _ = self.bert(input_ids, token_type_ids, attention_mask, output_all_encoded_layers=False, checkpoint_activations=checkpoint_activations)
-        logits = self.qa_outputs(sequence_output)
-        start_logits, end_logits = logits.split(1, dim=-1)
-        start_logits = start_logits.squeeze(-1)
-        end_logits = end_logits.squeeze(-1)
-
-        if start_positions is not None and end_positions is not None:
-            # If we are on multi-GPU, split add a dimension
-            if len(start_positions.size()) > 1:
-                start_positions = start_positions.squeeze(-1)
-            if len(end_positions.size()) > 1:
-                end_positions = end_positions.squeeze(-1)
-            # sometimes the start/end positions are outside our model inputs, we ignore these terms
-            ignored_index = start_logits.size(1)
-            start_positions.clamp_(0, ignored_index)
-            end_positions.clamp_(0, ignored_index)
-
-            loss_fct = CrossEntropyLoss(ignore_index=ignored_index)
-            start_loss = loss_fct(start_logits, start_positions)
-            end_loss = loss_fct(end_logits, end_positions)
-            total_loss = (start_loss + end_loss) / 2
-            return total_loss
-        else:
-            return start_logits, end_logits
-
-
-
-

megatron/model/transformer.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Transformer."""
+
+import math
+
+import torch
+from apex.normalization.fused_layer_norm import FusedLayerNorm as LayerNorm
+
+from megatron import mpu
+from megatron.module import MegatronModule
+
+
+""" We use the following notation throughout this file:
+     h: hidden size
+     n: number of attention heads
+     p: number of model parallel partitions
+     np: n/p
+     hp: h/p
+     hn: h/n
+     b: batch size
+     s: sequence length
+     l: number of layers
+    Transformer takes input of size [b, s, h] and returns a
+    tensor of the same size. We use the following arguments:
+        hyperparameters: transformer hyperparameters
+        attention_mask_func: a function that takes `unmaksed-attention-scores`
+            with size [b, np, s, s] and an `attention-mask` and will apply
+            the masking. The function should return a masked score of the
+            same size [b, np, s, s].
+               masked-attention-scores = attention_mask_func(
+                                     unmaksed-attention-scores, attention-mask)
+"""
+
+
+class TransformerHyperparameters:
+    """Hyperparameters used to build and run the transformer.
+
+    Arguments:
+        hidden_size: hidden size (h)
+        num_layers: number of layers (l)
+        num_attention_heads: number of attention heads (n)
+        attention_dropout_prob: dropout probability for the attention
+                                probabiliies
+        output_dropout_prob: dropout probability for the output
+                             layers (attention output and mlp output)
+        mlp_activation_func: activation function for the mlp layer
+        layernorm_epsilon: tolerance parameters used for layer norm
+                           dividions
+        init_method: init method used for all weights except layer
+                     norm and output weights
+        output_layer_init_method: init method for output weights (
+                                  attention output and mlp output)
+        checkpoint_activations: flag to use activation checkpointing
+        checkpoint_num_layers: number of layers use in each chunk of
+                               activation checkpointing
+        apply_residual_connection_post_layernorm: Take the post layer-norm
+            values for resudual connecton. BERT: True, GPT-2: False
+    """
+    def __init__(self,
+                 hidden_size=None,
+                 num_layers=None,
+                 num_attention_heads=None,
+                 attention_dropout_prob=None,
+                 output_dropout_prob=None,
+                 mlp_activation_func=None,
+                 layernorm_epsilon=None,
+                 init_method=None,
+                 output_layer_init_method=None,
+                 checkpoint_activations=None,
+                 checkpoint_num_layers=None,
+                 apply_residual_connection_post_layernorm=None):
+        self.params_dict = {}
+        self.params_dict['hidden_size'] = hidden_size
+        self.params_dict['num_layers'] = num_layers
+        self.params_dict['num_attention_heads'] = num_attention_heads
+        self.params_dict['attention_dropout_prob'] = attention_dropout_prob
+        self.params_dict['output_dropout_prob'] = output_dropout_prob
+        self.params_dict['mlp_activation_func'] = mlp_activation_func
+        self.params_dict['layernorm_epsilon'] = layernorm_epsilon
+        self.params_dict['init_method'] = init_method
+        self.params_dict['output_layer_init_method'] = output_layer_init_method
+        self.params_dict['checkpoint_activations'] = checkpoint_activations
+        self.params_dict['checkpoint_num_layers'] = checkpoint_num_layers
+        self.params_dict['apply_residual_connection_post_layernorm'] \
+            = apply_residual_connection_post_layernorm
+
+
+    def __getitem__(self, key):
+        """Custom retrieval with error checks."""
+        try:
+            value = self.params_dict[key]
+        except KeyError:
+            raise Exception(
+                'could not find {} in transformer hyperparameters'.format(key))
+        except Exception as e:
+            print('unexpected error in transformer hyperparameters:', e)
+            raise Exception()
+        else:
+            assert value is not None, \
+                'parameter value for {} is not set in transformer '\
+                'hyperparameters'.format(key)
+            return value
+        raise Exception('should not be here')
+
+
+
+class ParallelMLP(MegatronModule):
+    """MLP.
+
+    MLP will take the input with h hidden state, project it to 4*h
+    hidden dimension, perform nonlinear transformation, and project the
+    state back into h hidden dimension. At the end, dropout is also
+    applied.
+    """
+
+    def __init__(self, hyperparameters):
+        super(ParallelMLP, self).__init__()
+
+        # Project to 4h.
+        self.dense_h_to_4h = mpu.ColumnParallelLinear(
+            hyperparameters['hidden_size'],
+            4*hyperparameters['hidden_size'],
+            gather_output=False,
+            init_method=hyperparameters['init_method'])
+
+        self.activation_func = hyperparameters['mlp_activation_func']
+
+        # Project back to h.
+        self.dense_4h_to_h = mpu.RowParallelLinear(
+            4*hyperparameters['hidden_size'],
+            hyperparameters['hidden_size'],
+            input_is_parallel=True,
+            init_method=hyperparameters['output_layer_init_method'])
+
+        self.dropout = torch.nn.Dropout(hyperparameters['output_dropout_prob'])
+
+
+    def forward(self, hidden_states):
+
+        # [b, s, 4hp]
+        intermediate_parallel = self.dense_h_to_4h(hidden_states)
+        intermediate_parallel = self.activation_func(intermediate_parallel)
+
+        # [b, s, h]
+        output = self.dense_4h_to_h(intermediate_parallel)
+        output = self.dropout(output)
+        return output
+
+
+
+class ParallelSelfAttention(MegatronModule):
+    """Parallel self-attention layer abstract class.
+
+    Self-attention layer takes input with size [b, s, h]
+    and returns output of the same size.
+    """
+
+    def __init__(self, hyperparameters, attention_mask_func):
+        super(ParallelSelfAttention, self).__init__()
+
+        self.attention_mask_func = attention_mask_func
+
+        # Per attention head and per partition values.
+        world_size = mpu.get_model_parallel_world_size()
+        self.hidden_size_per_partition = mpu.divide(
+            hyperparameters['hidden_size'], world_size)
+        self.hidden_size_per_attention_head = mpu.divide(
+            hyperparameters['hidden_size'],
+            hyperparameters['num_attention_heads'])
+        self.num_attention_heads_per_partition = mpu.divide(
+            hyperparameters['num_attention_heads'], world_size)
+
+        # Strided linear layer.
+        self.query_key_value = mpu.ColumnParallelLinear(
+            hyperparameters['hidden_size'],
+            3*hyperparameters['hidden_size'],
+            stride=3,
+            gather_output=False,
+            init_method=hyperparameters['init_method'])
+
+        # Dropout. Note that for a single iteration, this layer will generate
+        # different outputs on different number of parallel partitions but
+        # on average it should not be partition dependent.
+        self.attention_dropout = torch.nn.Dropout(
+            hyperparameters['attention_dropout_prob'])
+
+        # Output.
+        self.dense = mpu.RowParallelLinear(
+            hyperparameters['hidden_size'],
+            hyperparameters['hidden_size'],
+            input_is_parallel=True,
+            init_method=hyperparameters['output_layer_init_method'])
+        self.output_dropout = torch.nn.Dropout(
+            hyperparameters['output_dropout_prob'])
+
+
+    def _transpose_for_scores(self, tensor):
+        """Transpose a 3D tensor [b, s, np*hn] into a 4D tensor with
+        size [b, np, s, hn].
+        """
+        new_tensor_shape = tensor.size()[:-1] + \
+                           (self.num_attention_heads_per_partition,
+                            self.hidden_size_per_attention_head)
+        tensor = tensor.view(*new_tensor_shape)
+        return tensor.permute(0, 2, 1, 3)
+
+
+    def _get_query_key_value(self, hidden_states):
+        """Get query, key, and value and transpose to
+        get size [b, np, s, hn].
+        """
+        # Attention heads. [b, s, hp]
+        mixed_x_layer = self.query_key_value(hidden_states)
+        (mixed_query_layer,
+         mixed_key_layer,
+         mixed_value_layer) = mpu.split_tensor_along_last_dim(mixed_x_layer, 3)
+
+        # Reshape and transpose [b, np, s, hn]
+        query_layer = self._transpose_for_scores(mixed_query_layer)
+        key_layer = self._transpose_for_scores(mixed_key_layer)
+        value_layer = self._transpose_for_scores(mixed_value_layer)
+
+        return query_layer, key_layer, value_layer
+
+
+    def _get_unmasked_attention_scores(self, query_layer, key_layer):
+        """Unmasked attention scores with size [b, np, s, s]."""
+        norm_factor = math.sqrt(math.sqrt(self.hidden_size_per_attention_head))
+        # Raw attention scores. [b, np, s, s]
+        return torch.matmul(query_layer/norm_factor,
+                            key_layer.transpose(-1, -2)/norm_factor)
+
+
+    def _get_attention_probs(self, attention_scores):
+        """Attention probabilies with dropout. The output has
+        the size [b, np, s, s].
+        """
+        # Attention probabilities. [b, np, s, s]
+        attention_probs = torch.nn.Softmax(dim=-1)(attention_scores)
+        # This is actually dropping out entire tokens to attend to, which might
+        # seem a bit unusual, but is taken from the original Transformer paper.
+        with mpu.get_cuda_rng_tracker().fork():
+            attention_probs = self.attention_dropout(attention_probs)
+
+        return attention_probs
+
+
+    def _get_attended_context(self, attention_probs, value_layer):
+        """Final attended tesnor and transposed back to [b, s, hp]."""
+        # Context layer.
+        # [b, np, s, hn]
+        context_layer = torch.matmul(attention_probs, value_layer)
+        # [b, s, np, hn]
+        context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
+        new_context_layer_shape = context_layer.size()[:-2] + \
+                                  (self.hidden_size_per_partition,)
+        # [b, s, hp]
+        context_layer = context_layer.view(*new_context_layer_shape)
+
+        return context_layer
+
+
+    def _get_output(self, context_layer):
+        """Output layer with dropout."""
+        # Output. [b, s, h]
+        output = self.dense(context_layer)
+        output = self.output_dropout(output)
+
+        return output
+
+
+    def forward(self, hidden_states, attention_mask, layer_past=None,
+                get_key_value=False):
+        # hidden_states: [b, s, h]
+
+        # Attention heads. [b, np, s, hn]
+        query_layer, key_layer, value_layer = self._get_query_key_value(
+            hidden_states)
+
+        if layer_past is not None:
+            past_key, past_value = layer_past
+            key_layer = torch.cat((past_key.type_as(key_layer),
+                                   key_layer), dim=-2)
+            value_layer = torch.cat((past_value.type_as(value_layer),
+                                     value_layer), dim=-2)
+        if get_key_value:
+            present = (key_layer, value_layer)
+
+        # Raw attention scores. [b, np, s, s]
+        attention_scores = self._get_unmasked_attention_scores(
+            query_layer, key_layer)
+
+        # Apply attention mask. [b, np, s, s]
+        if get_key_value:
+            with torch.no_grad():
+                if layer_past is not None:
+                    attention_mask = attention_mask[
+                        ...,
+                        attention_scores.size(3)-1,
+                        :attention_scores.size(3)].unsqueeze(2)
+                else:
+                    attention_mask = attention_mask[
+                        ...,
+                        :attention_scores.size(3),
+                        :attention_scores.size(3)]
+        attention_scores = self.attention_mask_func(attention_scores,
+                                                    attention_mask)
+
+        # Attention probabilities. [b, np, s, s]
+        attention_probs = self._get_attention_probs(attention_scores)
+
+        # Context layer. [b, s, hp]
+        context_layer = self._get_attended_context(attention_probs, value_layer)
+
+        # Output. [b, s, h]
+        output = self._get_output(context_layer)
+
+        if get_key_value:
+            output = [output, present]
+
+        return output
+
+
+
+class ParallelTransformerLayer(MegatronModule):
+    """A single transformer layer.
+
+    Transformore layer takes input with size [b, s, h] and returns an
+    output of the same size.
+    """
+    def __init__(self, hyperparameters, attention_mask_func):
+
+        super(ParallelTransformerLayer, self).__init__()
+
+        self.apply_residual_connection_post_layernorm \
+            = hyperparameters['apply_residual_connection_post_layernorm']
+
+        # Layernorm on the input data.
+        self.input_layernorm = LayerNorm(
+            hyperparameters['hidden_size'],
+            eps=hyperparameters['layernorm_epsilon'])
+
+        # Self attention.
+        self.attention = ParallelSelfAttention(
+            hyperparameters,
+            attention_mask_func)
+
+        # Layernorm on the input data.
+        self.post_attention_layernorm = LayerNorm(
+            hyperparameters['hidden_size'],
+            eps=hyperparameters['layernorm_epsilon'])
+
+        # MLP
+        self.mlp = ParallelMLP(hyperparameters)
+
+
+    def forward(self, hidden_states, attention_mask, layer_past=None,
+                get_key_value=False):
+        # hidden_states: [b, s, h]
+
+        # Layer norm at the begining of the transformer layer.
+        layernorm_output = self.input_layernorm(hidden_states)
+        # Self attention.
+        attention_output = self.attention(layernorm_output,
+                                          attention_mask,
+                                          layer_past=layer_past,
+                                          get_key_value=get_key_value)
+        if get_key_value:
+            attention_output, presents = attention_output
+
+        # Residual connection.
+        if self.apply_residual_connection_post_layernorm:
+            layernorm_input = layernorm_output + attention_output
+        else:
+            layernorm_input = hidden_states + attention_output
+        # Layer norm post the self attention.
+        layernorm_output = self.post_attention_layernorm(layernorm_input)
+
+        # MLP.
+        mlp_output = self.mlp(layernorm_output)
+        # Second residual connection.
+        if self.apply_residual_connection_post_layernorm:
+            output = layernorm_output + mlp_output
+        else:
+            output = layernorm_input + mlp_output
+
+        if get_key_value:
+            output = [output, presents]
+
+        return output
+
+
+class ParallelTransformer(MegatronModule):
+    """Transformer class."""
+
+    def __init__(self, hyperparameters, attention_mask_func):
+        super(ParallelTransformer, self).__init__()
+
+        # Store activation checkpoiting flag.
+        self.checkpoint_activations = hyperparameters['checkpoint_activations']
+        self.checkpoint_num_layers = hyperparameters['checkpoint_num_layers']
+
+        def get_layer():
+            return ParallelTransformerLayer(
+                hyperparameters,
+                attention_mask_func)
+
+        # Transformer layers.
+        self.layers = torch.nn.ModuleList(
+            [get_layer() for _ in range(hyperparameters['num_layers'])])
+
+        # Final layer norm before output.
+        self.final_layernorm = LayerNorm(
+            hyperparameters['hidden_size'],
+            eps=hyperparameters['layernorm_epsilon'])
+
+
+    def _checkpointed_forward(self, hidden_states, attention_mask):
+        """Forward method with activation checkpointing."""
+        def custom(start, end):
+            def custom_forward(*inputs):
+                layers_ = self.layers[start:end]
+                x_ = inputs[0]
+                for layer in layers_:
+                    x_ = layer(x_, inputs[1])
+                return x_
+            return custom_forward
+
+        l = 0
+        num_layers = len(self.layers)
+        while l < num_layers:
+            hidden_states = mpu.checkpoint(
+                custom(l, l+self.checkpoint_num_layers),
+                hidden_states, attention_mask)
+            l += self.checkpoint_num_layers
+
+        return hidden_states
+
+
+    def forward(self, hidden_states, attention_mask, layer_past=None,
+                get_key_value=False):
+
+        # Checks
+        if layer_past is not None:
+            assert get_key_value, \
+                'for not None values in layer_past, ' \
+                'expected get_key_value to be set'
+        if get_key_value:
+            assert not self.checkpoint_activations, \
+                'get_key_value does not work with ' \
+                'activation checkpointing'
+
+        if self.checkpoint_activations:
+            hidden_states = self._checkpointed_forward(hidden_states,
+                                                       attention_mask)
+        else:
+            if get_key_value:
+                presents = []
+            for i, layer in enumerate(self.layers):
+                past = None
+                if layer_past is not None:
+                    past = layer_past[i]
+                hidden_states = layer(hidden_states,
+                                      attention_mask,
+                                      layer_past=past,
+                                      get_key_value=get_key_value)
+                if get_key_value:
+                    hidden_states, present = hidden_states
+                    presents.append(present)
+
+        # Final layer norm.
+        output = self.final_layernorm(hidden_states)
+        if get_key_value:
+            output = [output, presents]
+
+        return output

megatron/model/model.py → megatron/model/utils.py

@@ -13,21 +13,59 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-"""Utilities for wrapping BertModel."""
+"""Utilities for models."""
+
+import math
 
 import torch
 
-from .modeling import BertConfig
-from .modeling import BertForPreTraining, BertForMaskedLM
-from .modeling import BertLayerNorm
+from .transformer import LayerNorm
 
 
-def get_params_for_weight_decay_optimization(module):
+def init_method_normal(sigma):
+    """Init method based on N(0, sigma)."""
+    def init_(tensor):
+        return torch.nn.init.normal_(tensor, mean=0.0, std=sigma)
+
+    return init_
+
+
+def scaled_init_method_normal(sigma, num_layers):
+    """Init method based on N(0, sigma/sqrt(2*num_layers)."""
+    std = sigma / math.sqrt(2.0 * num_layers)
+    def init_(tensor):
+        return torch.nn.init.normal_(tensor, mean=0.0, std=std)
+
+    return init_
+
+
+def get_linear_layer(rows, columns, init_method):
+    """Simple linear layer with weight initialization."""
+    layer = torch.nn.Linear(rows, columns)
+    init_method(layer.weight)
+    with torch.no_grad():
+        layer.bias.zero_()
+    return layer
+
+
+@torch.jit.script
+def gelu_impl(x):
+    """OpenAI's gelu implementation."""
+    return 0.5 * x * (1.0 + torch.tanh(0.7978845608028654 * x *
+                                       (1.0 + 0.044715 * x * x)))
 
+def gelu(x):
+    return gelu_impl(x)
+
+
+def get_params_for_weight_decay_optimization(module):
+    """Divide params into with-weight-decay and without-weight-decay groups.
+    Layernorms and baises will have no weight decay but the rest will.
+    """
     weight_decay_params = {'params': []}
     no_weight_decay_params = {'params': [], 'weight_decay': 0.0}
     for module_ in module.modules():
-        if isinstance(module_, (BertLayerNorm, torch.nn.LayerNorm)):
+        if isinstance(module_, LayerNorm):
             no_weight_decay_params['params'].extend(
                 [p for p in list(module_._parameters.values())
                  if p is not None])
@@ -40,51 +78,3 @@ def get_params_for_weight_decay_optimization(module):
                  if p is not None and n == 'bias'])
 
     return weight_decay_params, no_weight_decay_params
-
-
-class BertModel(torch.nn.Module):
-
-    def __init__(self, args):
-        super(BertModel, self).__init__()
-        if args.pretrained_bert:
-            self.model = BertForPreTraining.from_pretrained(
-                args.tokenizer_model_type,
-                cache_dir=args.cache_dir,
-                fp32_layernorm=args.fp32_layernorm,
-                fp32_embedding=args.fp32_embedding,
-                layernorm_epsilon=args.layernorm_epsilon)
-        else:
-            if args.intermediate_size is None:
-                intermediate_size = 4 * args.hidden_size
-            else:
-                intermediate_size = args.intermediate_size
-            self.config = BertConfig(
-                args.tokenizer_num_tokens,
-                hidden_size=args.hidden_size,
-                num_hidden_layers=args.num_layers,
-                num_attention_heads=args.num_attention_heads,
-                intermediate_size=intermediate_size,
-                hidden_dropout_prob=args.hidden_dropout,
-                attention_probs_dropout_prob=args.attention_dropout,
-                max_position_embeddings=args.max_position_embeddings,
-                type_vocab_size=args.tokenizer_num_type_tokens,
-                fp32_layernorm=args.fp32_layernorm,
-                fp32_embedding=args.fp32_embedding,
-                fp32_tokentypes=args.fp32_tokentypes,
-                layernorm_epsilon=args.layernorm_epsilon,
-                deep_init=args.deep_init)
-            self.model = BertForPreTraining(self.config)
-
-    def forward(self, input_tokens, token_type_ids=None,
-                attention_mask=None, checkpoint_activations=False):
-        return self.model(
-            input_tokens, token_type_ids, attention_mask,
-            checkpoint_activations=checkpoint_activations)
-
-    def state_dict(self, destination=None, prefix='', keep_vars=False):
-        return self.model.state_dict(destination=destination, prefix=prefix,
-                                     keep_vars=keep_vars)
-
-    def load_state_dict(self, state_dict, strict=True):
-        return self.model.load_state_dict(state_dict, strict=strict)
-

megatron/module.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+"""Megatron Module"""
+
+import torch
+
+
+class MegatronModule(torch.nn.Module):
+    """Megatron specific extentions of torch Module."""
+
+
+    def __init__(self):
+        super(MegatronModule, self).__init__()
+
+
+    def state_dict_for_save_checkpoint(self, destination=None, prefix='',
+                                       keep_vars=False):
+        """Use this function to override the state dict for
+        saving checkpoints."""
+        return self.state_dict(destination, prefix, keep_vars)

megatron/mpu/__init__.py

@@ -46,7 +46,5 @@ from .random import checkpoint
 from .random import get_cuda_rng_tracker
 from .random import model_parallel_cuda_manual_seed
 
-from .transformer import BertParallelSelfAttention
-from .transformer import BertParallelTransformerLayer
-from .transformer import GPT2ParallelTransformer
-from .transformer import LayerNorm
+from .utils import divide
+from .utils import split_tensor_along_last_dim

megatron/mpu/transformer.py

-# coding=utf-8
-# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""Transformer."""
-
-import math
-
-import torch
-import torch.nn.init as init
-from apex.normalization.fused_layer_norm import FusedLayerNorm as LayerNorm
-
-from .initialize import get_model_parallel_world_size
-from .layers import ColumnParallelLinear
-from .layers import RowParallelLinear
-from .mappings import gather_from_model_parallel_region
-from .random import checkpoint
-from .random import get_cuda_rng_tracker
-from .utils import divide
-from .utils import split_tensor_along_last_dim
-
-
-class GPT2ParallelSelfAttention(torch.nn.Module):
-    """Parallel self-attention layer for GPT2.
-
-    Self-attention layer takes input with size [b, s, h] where b is
-    the batch size, s is the sequence lenght, and h is the hidden size
-    and creates output of the same size.
-    Arguments:
-        hidden_size: total hidden size of the layer (h).
-        num_attention_heads: number of attention heads (n). Note that we
-                             require n to be divisible by number of GPUs
-                             used to parallelize the model. Also, we
-                             require hidden size to be divisible by n.
-        dropout_prob: dropout probability for the attention scores.
-        init_method: weight initialization.
-        output_layer_init_method: output layer initialization. If None, use
-                                  `init_method`.
-    We use the following notation:
-        h: hidden_size
-        n: num_attention_heads
-        p: number of partitions
-        np: n/p
-        hp: h/p
-        hn: h/n
-        b: batch size
-        s: sequence length
-    """
-    def __init__(self, hidden_size, num_attention_heads,
-                 attention_dropout_prob, output_dropout_prob,
-                 init_method, output_layer_init_method=None):
-        super(GPT2ParallelSelfAttention, self).__init__()
-        # Set output layer initialization if not provided.
-        if output_layer_init_method is None:
-            output_layer_init_method = init_method
-        # Per attention head and per partition values.
-        world_size = get_model_parallel_world_size()
-        self.hidden_size_per_partition = divide(hidden_size, world_size)
-        self.hidden_size_per_attention_head = divide(hidden_size,
-                                                     num_attention_heads)
-        self.num_attention_heads_per_partition = divide(num_attention_heads,
-                                                        world_size)
-        # Strided linear layer.
-        self.query_key_value = ColumnParallelLinear(hidden_size, 3*hidden_size,
-                                                    stride=3,
-                                                    gather_output=False,
-                                                    init_method=init_method)
-        # Dropout. Note that for a single iteration, this layer will generate
-        # different outputs on different number of parallel partitions but
-        # on average it should not be partition dependent.
-        self.attention_dropout = torch.nn.Dropout(attention_dropout_prob)
-
-        # Output.
-        self.dense = RowParallelLinear(hidden_size,
-                                       hidden_size,
-                                       input_is_parallel=True,
-                                       init_method=output_layer_init_method)
-        self.output_dropout = torch.nn.Dropout(output_dropout_prob)
-
-    def _transpose_for_scores(self, tensor):
-        """Transpose a 3D tensor [b, s, np*hn] into a 4D tensor with
-        size [b, np, s, hn].
-        """
-        new_tensor_shape = tensor.size()[:-1] + \
-                           (self.num_attention_heads_per_partition,
-                            self.hidden_size_per_attention_head)
-        tensor = tensor.view(*new_tensor_shape)
-        return tensor.permute(0, 2, 1, 3)
-
-    def forward(self, hidden_states, ltor_mask, layer_past=None, get_present=False):
-        # hidden_states: [b, s, h]
-        # ltor_mask: [1, 1, s, s]
-
-        # Attention heads. [b, s, hp]
-        mixed_x_layer = self.query_key_value(hidden_states)
-        (mixed_query_layer,
-         mixed_key_layer,
-         mixed_value_layer) = split_tensor_along_last_dim(mixed_x_layer, 3)
-
-        # Reshape and transpose [b, np, s, hn]
-        query_layer = self._transpose_for_scores(mixed_query_layer)
-        key_layer = self._transpose_for_scores(mixed_key_layer)
-        value_layer = self._transpose_for_scores(mixed_value_layer)
-        if layer_past is not None:
-            past_key, past_value = layer_past
-            key_layer = torch.cat((past_key.type_as(key_layer), key_layer), dim=-2)
-            value_layer = torch.cat((past_value.type_as(value_layer), value_layer), dim=-2)
-        present = (key_layer, value_layer)
-
-        # Raw attention scores. [b, np, s, s]
-        norm_factor = math.sqrt(math.sqrt(self.hidden_size_per_attention_head))
-        attention_scores = torch.matmul(query_layer/norm_factor,
-                                        key_layer.transpose(-1, -2)/norm_factor)
-                                        
-        # Apply the left to right attention mask.
-        if get_present:
-            with torch.no_grad():
-                if layer_past is not None:
-                    ltor_mask = ltor_mask[...,attention_scores.size(3)-1, :attention_scores.size(3)].unsqueeze(2)
-                else:
-                    ltor_mask = ltor_mask[...,:attention_scores.size(3), :attention_scores.size(3)]
-        attention_scores = torch.mul(attention_scores, ltor_mask) - \
-                           10000.0 * (1.0 - ltor_mask)
-
-        # Attention probabilities. [b, np, s, s]
-        attention_probs = torch.nn.Softmax(dim=-1)(attention_scores)
-        # This is actually dropping out entire tokens to attend to, which might
-        # seem a bit unusual, but is taken from the original Transformer paper.
-        with get_cuda_rng_tracker().fork():
-            attention_probs = self.attention_dropout(attention_probs)
-
-        # Context layer.
-        # [b, np, s, hn]
-        context_layer = torch.matmul(attention_probs, value_layer)
-        # [b, s, np, hn]
-        context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
-        new_context_layer_shape = context_layer.size()[:-2] + \
-                                  (self.hidden_size_per_partition,)
-        # [b, s, hp]
-        context_layer = context_layer.view(*new_context_layer_shape)
-
-        # Output. [b, s, h]
-        output = self.dense(context_layer)
-        output = self.output_dropout(output)
-
-        if get_present:
-            output = [output, present]
-
-        return output
-
-
-@torch.jit.script
-def gelu_impl(x):
-     """OpenAI's gelu implementation."""
-     return 0.5 * x * (1.0 + torch.tanh(0.7978845608028654 * x *
-                                        (1.0 + 0.044715 * x * x)))
-
-def gelu(x):
-    return gelu_impl(x)
-
-
-class GPT2ParallelMLP(torch.nn.Module):
-    """MLP for GPT2.
-
-    MLP will take the input with h hidden state, project it to 4*h
-    hidden dimension, perform gelu transformation, and project the
-    state back into h hidden dimension. At the end, dropout is also
-    applied.
-
-    Arguments:
-        hidden_size: The hidden size of the self attention.
-        output_dropout_prob: dropout probability for the outputs
-                             after self attention and final output.
-        init_method: initialization method used for the weights. Note
-                     that all biases are initialized to zero and
-                     layernorm weight are initialized to one.
-        output_layer_init_method: output layer initialization. If None,
-                                  use `init_method`.
-    """
-
-    def __init__(self, hidden_size, output_dropout_prob, init_method,
-                 output_layer_init_method=None):
-        super(GPT2ParallelMLP, self).__init__()
-        # Set output layer initialization if not provided.
-        if output_layer_init_method is None:
-            output_layer_init_method = init_method
-        # Project to 4h.
-        self.dense_h_to_4h = ColumnParallelLinear(hidden_size, 4*hidden_size,
-                                                  gather_output=False,
-                                                  init_method=init_method)
-        # Project back to h.
-        self.dense_4h_to_h = RowParallelLinear(
-            4*hidden_size,
-            hidden_size,
-            input_is_parallel=True,
-            init_method=output_layer_init_method)
-        self.dropout = torch.nn.Dropout(output_dropout_prob)
-
-    def forward(self, hidden_states):
-        # [b, s, 4hp]
-        intermediate_parallel = self.dense_h_to_4h(hidden_states)
-        intermediate_parallel = gelu(intermediate_parallel)
-
-        # [b, s, h]
-        output = self.dense_4h_to_h(intermediate_parallel)
-        output = self.dropout(output)
-        return output
-
-
-class GPT2ParallelTransformerLayer(torch.nn.Module):
-    """A single layer transformer for GPT2.
-
-    We use the following notation:
-        h: hidden size
-        n: number of attention heads
-        b: batch size
-        s: sequence length
-    Transformore layer takes input with size [b, s, h] and returns an
-    output of the same size.
-
-    Arguments:
-        hidden_size: The hidden size of the self attention.
-        num_attention_heads: number of attention head in the self
-                             attention.
-        attention_dropout_prob: dropout probability of the attention
-                                score in self attention.
-        output_dropout_prob: dropout probability for the outputs
-                             after self attention and final output.
-        layernorm_epsilon: epsilon used in layernorm to avoid
-                           division by zero.
-        init_method: initialization method used for the weights. Note
-                     that all biases are initialized to zero and
-                     layernorm weight are initialized to one.
-        output_layer_init_method: output layers (attention output and
-                                  mlp output) initialization. If None,
-                                  use `init_method`.
-    """
-    def __init__(self,
-                 hidden_size,
-                 num_attention_heads,
-                 attention_dropout_prob,
-                 output_dropout_prob,
-                 layernorm_epsilon,
-                 init_method,
-                 output_layer_init_method=None):
-        super(GPT2ParallelTransformerLayer, self).__init__()
-        # Set output layer initialization if not provided.
-        if output_layer_init_method is None:
-            output_layer_init_method = init_method
-
-        # Layernorm on the input data.
-        self.input_layernorm = LayerNorm(hidden_size, eps=layernorm_epsilon)
-
-        # Self attention.
-        self.attention = GPT2ParallelSelfAttention(
-            hidden_size,
-            num_attention_heads,
-            attention_dropout_prob,
-            output_dropout_prob,
-            init_method,
-            output_layer_init_method=output_layer_init_method)
-
-        # Layernorm on the input data.
-        self.post_attention_layernorm = LayerNorm(hidden_size,
-                                                  eps=layernorm_epsilon)
-
-        # MLP
-        self.mlp = GPT2ParallelMLP(
-            hidden_size,
-            output_dropout_prob,
-            init_method,
-            output_layer_init_method=output_layer_init_method)
-
-    def forward(self, hidden_states, ltor_mask, layer_past=None, get_present=False):
-        # hidden_states: [b, s, h]
-        # ltor_mask: [1, 1, s, s]
-
-        # Layer norm at the begining of the transformer layer.
-        layernorm_output = self.input_layernorm(hidden_states)
-        # Self attention.
-        attention_output = self.attention(layernorm_output, ltor_mask, layer_past=layer_past, get_present=get_present)
-        if get_present:
-            attention_output, presents = attention_output
-        # Residual connection.
-        layernorm_input = hidden_states + attention_output
-        # Layer norm post the self attention.
-        layernorm_output = self.post_attention_layernorm(layernorm_input)
-        # MLP.
-        mlp_output = self.mlp(layernorm_output)
-        # Second residual connection.
-        output = layernorm_input + mlp_output
-
-        if get_present:
-            output = [output, presents]
-
-        return output
-
-
-def unscaled_init_method(sigma):
-    """Init method based on N(0, sigma)."""
-    def init_(tensor):
-        return torch.nn.init.normal_(tensor, mean=0.0, std=sigma)
-
-    return init_
-
-
-def scaled_init_method(sigma, num_layers):
-    """Init method based on N(0, sigma/sqrt(2*num_layers)."""
-    std = sigma / math.sqrt(2.0 * num_layers)
-    def init_(tensor):
-        return torch.nn.init.normal_(tensor, mean=0.0, std=std)
-
-    return init_
-
-
-class GPT2ParallelTransformer(torch.nn.Module):
-    """GPT-2 transformer.
-
-    This module takes input from embedding layer and it's output can
-    be used directly by a logit layer. It consists of L (num-layers)
-    blocks of:
-        layer norm
-        self attention
-        residual connection
-        layer norm
-        mlp
-        residual connection
-    followed by a final layer norm.
-
-    Arguments:
-        num_layers: Number of transformer layers.
-        hidden_size: The hidden size of the self attention.
-        num_attention_heads: number of attention head in the self
-                             attention.
-        attention_dropout_prob: dropout probability of the attention
-                                score in self attention.
-        output_dropout_prob: dropout probability for the outputs
-                             after self attention and final output.
-        checkpoint_activations: if True, checkpoint activations.
-        checkpoint_num_layers: number of layers to checkpoint. This
-                               is basically the chunk size in checkpoitning.
-        layernorm_epsilon: epsilon used in layernorm to avoid
-                           division by zero.
-        init_method_std: standard deviation of the init method which has
-                         the form N(0, std).
-        use_scaled_init_for_output_weights: If Ture use 1/sqrt(2*num_layers)
-                                            scaling for the output weights (
-                                            output of self attention and mlp).
-    """
-    def __init__(self,
-                 num_layers,
-                 hidden_size,
-                 num_attention_heads,
-                 attention_dropout_prob,
-                 output_dropout_prob,
-                 checkpoint_activations,
-                 checkpoint_num_layers=1,
-                 layernorm_epsilon=1.0e-5,
-                 init_method_std=0.02,
-                 use_scaled_init_for_output_weights=True):
-        super(GPT2ParallelTransformer, self).__init__()
-        # Store activation checkpoiting flag.
-        self.checkpoint_activations = checkpoint_activations
-        self.checkpoint_num_layers = checkpoint_num_layers
-
-        output_layer_init_method = None
-        if use_scaled_init_for_output_weights:
-            output_layer_init_method = scaled_init_method(init_method_std,
-                                                          num_layers)
-        def get_layer():
-            return GPT2ParallelTransformerLayer(
-                hidden_size,
-                num_attention_heads,
-                attention_dropout_prob,
-                output_dropout_prob,
-                layernorm_epsilon,
-                unscaled_init_method(init_method_std),
-                output_layer_init_method=output_layer_init_method)
-
-        # Transformer layers.
-        self.layers = torch.nn.ModuleList(
-            [get_layer() for _ in range(num_layers)])
-
-        # Final layer norm before output.
-        self.final_layernorm = LayerNorm(hidden_size, eps=layernorm_epsilon)
-
-    def forward(self, hidden_states, attention_mask, layer_past=None, get_present=False):
-
-        def custom(start, end):
-            def custom_forward(*inputs):
-                layers_ = self.layers[start:end]
-                x_ = inputs[0]
-                for layer in layers_:
-                    x_ = layer(x_, inputs[1])
-                return x_
-            return custom_forward
-
-        if self.checkpoint_activations and not get_present:
-            l = 0
-            num_layers = len(self.layers)
-            chunk_length = self.checkpoint_num_layers
-            while l < num_layers:
-                hidden_states = checkpoint(custom(l, l+chunk_length),
-                                           hidden_states, attention_mask)
-                l += chunk_length
-        else:
-            presents = []
-            for i, layer in enumerate(self.layers):
-                past = None
-                if layer_past is not None:
-                    past = layer_past[i]
-                hidden_states = layer(hidden_states, attention_mask, layer_past=past, get_present=get_present)
-                if get_present:
-                    hidden_states, present = hidden_states
-                    presents.append(present)
-
-        # Final layer norm.
-        output = self.final_layernorm(hidden_states)
-        if get_present:
-            output = [output, presents]
-
-        return output
-
-
-class BertParallelSelfAttention(torch.nn.Module):
-    """Parallel self-attention layer for BERT.
-
-    Self-attention layer takes input with size [b, s, h] where b is
-    the batch size, s is the sequence lenght, and h is the hidden size
-    and creates output of the same size.
-    Arguments:
-        hidden_size: total hidden size of the layer (h).
-        num_attention_heads: number of attention heads (n). Note that we
-                             require n to be divisible by number of GPUs
-                             used to parallelize the model. Also, we
-                             require hidden size be divisible by n.
-        dropout_prob: dropout probability for the attention scores.
-        output_parallel: If true, no all-gather is done on the output and
-                         the output values will be per partition.
-    We use the following notation:
-        h: hidden_size
-        n: num_attention_heads
-        p: number of partitions
-        np: n/p
-        hp: h/p
-        hn: h/n
-        b: batch size
-        s: sequence length
-    """
-    def __init__(self, hidden_size, num_attention_heads,
-                 dropout_prob, output_parallel=False,
-                 init_method=init.xavier_normal_):
-        super(BertParallelSelfAttention, self).__init__()
-        # Input configuration.
-        self.hidden_size = hidden_size
-        self.num_attention_heads = num_attention_heads
-        self.dropout_prob = dropout_prob
-        self.output_parallel = output_parallel
-        # Per attention head and per partition values.
-        world_size = get_model_parallel_world_size()
-        self.hidden_size_per_partition = divide(hidden_size, world_size)
-        self.hidden_size_per_attention_head = divide(hidden_size,
-                                                     num_attention_heads)
-        self.num_attention_heads_per_partition = divide(num_attention_heads,
-                                                        world_size)
-        # Strided linear layer.
-        self.query_key_value = ColumnParallelLinear(hidden_size, 3*hidden_size,
-                                                    stride=3,
-                                                    gather_output=False,
-                                                    init_method=init_method)
-        # Dropout. Note that for a single iteration, this layer will generate
-        # different outputs on different number of parallel partitions but
-        # on average it should not be partition dependent.
-        self.dropout = torch.nn.Dropout(dropout_prob)
-
-    def _transpose_for_scores(self, tensor):
-        """Transpose a 3D tensor [b, s, np*hn] into a 4D tensor with
-        size [b, np, s, hn].
-        """
-        new_tensor_shape = tensor.size()[:-1] + \
-                           (self.num_attention_heads_per_partition,
-                            self.hidden_size_per_attention_head)
-        tensor = tensor.view(*new_tensor_shape)
-        return tensor.permute(0, 2, 1, 3)
-
-    def forward(self, hidden_states, attention_mask):
-
-        # Attention heads. [b, s, hp]
-        mixed_x_layer = self.query_key_value(hidden_states)
-        (mixed_query_layer,
-         mixed_key_layer,
-         mixed_value_layer) = split_tensor_along_last_dim(mixed_x_layer, 3)
-
-        # Reshape and transpose [b, np, s, hn]
-        query_layer = self._transpose_for_scores(mixed_query_layer)
-        key_layer = self._transpose_for_scores(mixed_key_layer)
-        value_layer = self._transpose_for_scores(mixed_value_layer)
-
-        # Raw attention scores. [b, np, s, s]
-        norm_factor = math.sqrt(math.sqrt(self.hidden_size_per_attention_head))
-        attention_scores = torch.matmul(query_layer/norm_factor,
-                                        key_layer.transpose(-1, -2)/norm_factor)
-        # Apply the attention mask.
-        attention_scores += attention_mask
-
-        # Attention probabilities. [b, np, s, s]
-        attention_probs = torch.nn.Softmax(dim=-1)(attention_scores)
-        # This is actually dropping out entire tokens to attend to, which might
-        # seem a bit unusual, but is taken from the original Transformer paper.
-        with get_cuda_rng_tracker().fork():
-            attention_probs = self.dropout(attention_probs)
-
-        # Context layer.
-        # [b, np, s, hn]
-        context_layer = torch.matmul(attention_probs, value_layer)
-        # [b, s, np, hn]
-        context_layer = context_layer.permute(0, 2, 1, 3).contiguous()
-        new_context_layer_shape = context_layer.size()[:-2] + \
-                                  (self.hidden_size_per_partition,)
-        # [b, s, hp]
-        context_layer = context_layer.view(*new_context_layer_shape)
-
-        # Output. [b, s, h]
-        if self.output_parallel:
-            output = context_layer
-        else:
-            output = gather_from_model_parallel_region(context_layer)
-
-        return output
-
-
-class BertParallelTransformerOutput(torch.nn.Module):
-    """The output layer used after self attention and intermediate
-    parts of transformer layer."""
-    def __init__(self, input_size, output_size, dropout_prob,
-                 layernorm_epsilon=1.0e-12, input_is_parallel=False,
-                 init_method=init.xavier_normal_):
-        super(BertParallelTransformerOutput, self).__init__()
-        # Components.
-        self.dense = RowParallelLinear(input_size,
-                                       output_size,
-                                       input_is_parallel=input_is_parallel,
-                                       init_method=init_method)
-        self.dropout = torch.nn.Dropout(dropout_prob)
-        self.layernorm = LayerNorm(output_size, eps=layernorm_epsilon)
-
-    def forward(self, hidden_states, input_tensor):
-        hidden_states = self.dense(hidden_states)
-        hidden_states = self.dropout(hidden_states)
-        layernorm_input = hidden_states + input_tensor
-        hidden_states = self.layernorm(layernorm_input)
-        return hidden_states
-
-
-class BertParallelTransformerLayer(torch.nn.Module):
-    """A single layer transformer for Bert.
-
-    We use the following notation:
-        h: hidden size
-        n: number of attention heads
-        b: batch size
-        s: sequence length
-    Transformore layer takes input with size [b, s, h] and returns an
-    output of the same size.
-
-    Arguments:
-        hidden_size: The hidden size of the self attention.
-        intermediate_size: size of the intermediate state after
-                           self attention. In both BERT and GPT
-                           this is set to be 4 times the hidden
-                           size.
-        num_attention_heads: number of attention head in the self
-                             attention.
-        attention_dropout_prob: dropout probability of the attention
-                                score in self attention.
-        output_dropout_prob: dropout probability for the outputs
-                             after self attention and final output.
-        intermediate_activation_fn: activation function for output
-                                    of intermediate.
-        layernorm_epsilon: epsilon used in layernorm to avoid
-                           division by zero.
-        init_method: initialization method used for the weights. Note
-                     that all biases are initialized to zero and
-                     layernorm weight are initialized to one.
-    """
-    def __init__(self,
-                 hidden_size,
-                 intermediate_size,
-                 num_attention_heads,
-                 attention_dropout_prob,
-                 output_dropout_prob,
-                 intermediate_activation_fn,
-                 layernorm_epsilon,
-                 init_method=init.xavier_normal_):
-        super(BertParallelTransformerLayer, self).__init__()
-
-        # Self attention.
-        self.attention = BertParallelSelfAttention(hidden_size,
-                                                   num_attention_heads,
-                                                   attention_dropout_prob,
-                                                   output_parallel=True,
-                                                   init_method=init_method)
-        # Self attention output.
-        self.self_output = BertParallelTransformerOutput(
-            hidden_size, hidden_size, output_dropout_prob,
-            layernorm_epsilon=layernorm_epsilon,
-            input_is_parallel=True,
-            init_method=init_method)
-        # Intermediate.
-        self.intermediate = ColumnParallelLinear(hidden_size, intermediate_size,
-                                                 gather_output=False,
-                                                 init_method=init_method)
-        self.intermediate_activation_fn = intermediate_activation_fn
-        # Output.
-        self.output = BertParallelTransformerOutput(
-            intermediate_size, hidden_size, output_dropout_prob,
-            layernorm_epsilon=layernorm_epsilon,
-            input_is_parallel=True,
-            init_method=init_method)
-
-    def forward(self, hidden_states, attention_mask):
-        # [b, s, hp]
-        attention_output_parallel = self.attention(hidden_states,
-                                                   attention_mask)
-        # [b, s, h]
-        attention_self_output = self.self_output(attention_output_parallel,
-                                                 hidden_states)
-        # [b, s, ip]
-        intermediate_output_parallel = self.intermediate(attention_self_output)
-        intermediate_output_parallel = self.intermediate_activation_fn(
-            intermediate_output_parallel)
-        # [b, s, h]
-        layer_output = self.output(intermediate_output_parallel,
-                                   attention_self_output)
-
-        return layer_output

megatron/training.py

+# coding=utf-8
+# Copyright (c) 2019, NVIDIA CORPORATION.  All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Pretrain utilities"""
+
+from datetime import datetime
+import math
+
+import torch
+from torch.nn.parallel.distributed import DistributedDataParallel as torchDDP
+from apex.optimizers import FusedAdam as Adam
+
+from arguments import get_args
+from megatron import mpu
+from megatron.fp16 import FP16_Module
+from megatron.fp16 import FP16_Optimizer
+from megatron.learning_rates import AnnealingLR
+from megatron.model import DistributedDataParallel as LocalDDP
+from megatron.model import get_params_for_weight_decay_optimization
+from megatron.utils import check_adlr_autoresume_termination
+from megatron.utils import enable_adlr_autoresume
+from megatron.utils import get_tensorboard_writer
+from megatron.utils import initialize_distributed
+from megatron.utils import load_checkpoint
+from megatron.utils import print_args
+from megatron.utils import print_rank_0
+from megatron.utils import report_memory
+from megatron.utils import save_checkpoint
+from megatron.utils import set_random_seed
+from megatron.utils import Timers
+
+
+def run(top_level_message, train_val_test_data_provider,
+        model_provider, forward_step_func):
+    """Main training program.
+
+    This function will run the followings in the order provided:
+        1) get input arguments.
+        2) initialize distributed and seeds.
+        3) call train_val_test_data_provider to get train/val/test datasets.
+        4) setup model, optimizer and lr schedule using the model_provider.
+        5) train the modle using the forward_step_func.
+
+    Arguments:
+        top_level_message: a meesage to print at the top of the run.
+        train_val_test_data_provider: a function that takes `args` as input
+            and returns `train, val, test` dataloaders. Note that args are
+            passed and can be modified in case we need to use some parameters
+            later. For example, we can set vocab size using
+                args.vocab_size = ...
+            and later use this value in `model_provider`.
+        model_provider: a function that takes `args` and returns a vanilla
+            version of the model. By vanilla we mean a simple model on cpu
+            with no fp16 or ddp.
+        forward_step_func: a function that takes a `data iterator`, `model`,
+            `args`, and `timers` and returns a `loss` scalar with a dictionary
+            with key:values being the info we would like to monitor during
+            training, for example `lm-loss: value`. We also require that this
+            function add `batch generator` to the timers class.
+    """
+
+    # Timer.
+    timers = Timers()
+
+    # Arguments.
+    args = get_args()
+
+    # Tensorboard writer
+    writer = get_tensorboard_writer(args)
+
+    # Pytorch distributed.
+    initialize_distributed(args)
+    if torch.distributed.get_rank() == 0:
+        print(top_level_message, flush=True)
+        print_args(args, writer)
+
+    # Autoresume.
+    torch.distributed.barrier()
+    if args.adlr_autoresume:
+        enable_adlr_autoresume(args)
+
+    # Random seeds for reproducability.
+    set_random_seed(args.seed)
+
+    # Data stuff.
+    train_data, val_data, test_data = train_val_test_data_provider(args)
+
+    # Model, optimizer, and learning rate.
+    model, optimizer, lr_scheduler = setup_model_and_optimizer(model_provider,
+                                                               args)
+
+    # Train, validation, and test data.
+    train_data_iterator, val_data_iterator, \
+        test_data_iterator = get_train_val_test_data_iterators(train_data,
+                                                               val_data,
+                                                               test_data,
+                                                               args)
+
+    iteration = 0
+    if args.train_iters > 0:
+        if args.do_train:
+            iteration, _ = train(forward_step_func, model,
+                                 optimizer, lr_scheduler,
+                                 train_data_iterator, val_data_iterator,
+                                 timers, args, writer)
+
+    if args.do_valid:
+        prefix = 'the end of training for val data'
+        evaluate_and_print_results(prefix, forward_step_func,
+                                   val_data_iterator, model,
+                                   args, writer, iteration,
+                                   timers, False)
+
+    if args.save and iteration != 0:
+        save_checkpoint(iteration, model, optimizer,
+                        lr_scheduler, args)
+
+    if args.do_test:
+        # Run on test data.
+        prefix = 'the end of training for test data'
+        evaluate_and_print_results(prefix, forward_step_func,
+                                   test_data_iterator, model,
+                                   args, None, 0, timers, True)
+
+
+def get_model(model_provider_func, args):
+    """Build the model."""
+
+    # Build model on cpu.
+    model = model_provider_func(args)
+
+    # Print number of parameters.
+    if mpu.get_data_parallel_rank() == 0:
+        print(' > number of parameters on model parallel rank {}: {}'.format(
+            mpu.get_model_parallel_rank(),
+            sum([p.nelement() for p in model.parameters()])), flush=True)
+
+    # GPU allocation.
+    model.cuda(torch.cuda.current_device())
+
+    # Fp16 conversion.
+    if args.fp16:
+        model = FP16_Module(model)
+
+    # Wrap model for distributed training."""
+    if args.DDP_impl == 'torch':
+        i = torch.cuda.current_device()
+        args.DDP_type = torchDDP
+        model = args.DDP_type(model, device_ids=[i], output_device=i,
+                              process_group=mpu.get_data_parallel_group())
+        return model
+    if args.DDP_impl == 'local':
+        args.DDP_type = LocalDDP
+        model = args.DDP_type(model)
+        return model
+
+    print_rank_0('Unknown DDP implementation specified: {}. '
+                 'Exiting.'.format(args.DDP_impl))
+    exit()
+    return model
+
+
+def get_optimizer(model, args):
+    """Set up the optimizer."""
+
+    # Build parameter groups (weight decay and non-decay).
+    while isinstance(model, (args.DDP_type, FP16_Module)):
+        model = model.module
+    param_groups = get_params_for_weight_decay_optimization(model)
+
+    # Add model parallel attribute if it is not set.
+    for param_group in param_groups:
+        for param in param_group['params']:
+            if not hasattr(param, 'model_parallel'):
+                param.model_parallel = False
+
+    # Use Adam.
+    optimizer = Adam(param_groups,
+                     lr=args.lr, weight_decay=args.weight_decay)
+
+    # Wrap into fp16 optimizer.
+    if args.fp16:
+        optimizer = FP16_Optimizer(optimizer,
+                                   static_loss_scale=args.loss_scale,
+                                   dynamic_loss_scale=args.dynamic_loss_scale,
+                                   dynamic_loss_args={
+                                       'scale_window': args.loss_scale_window,
+                                       'min_scale':args.min_scale,
+                                       'delayed_shift': args.hysteresis})
+
+    return optimizer
+
+
+def get_learning_rate_scheduler(optimizer, args):
+    """Build the learning rate scheduler."""
+
+    # Add linear learning rate scheduler.
+    if args.lr_decay_iters is not None:
+        num_iters = args.lr_decay_iters
+    else:
+        num_iters = args.train_iters
+    num_iters = max(1, num_iters)
+    init_step = -1
+    warmup_iter = args.warmup * num_iters
+    lr_scheduler = AnnealingLR(
+        optimizer,
+        start_lr=args.lr,
+        warmup_iter=warmup_iter,
+        num_iters=num_iters,
+        decay_style=args.lr_decay_style,
+        last_iter=init_step,
+        min_lr=args.min_lr,
+        use_checkpoint_lr_scheduler=args.use_checkpoint_lr_scheduler,
+        override_lr_scheduler=args.override_lr_scheduler)
+
+    return lr_scheduler
+
+
+def setup_model_and_optimizer(model_provider_func, args):
+    """Setup model and optimizer."""
+
+    model = get_model(model_provider_func, args)
+    optimizer = get_optimizer(model, args)
+    lr_scheduler = get_learning_rate_scheduler(optimizer, args)
+
+    if args.load is not None:
+        args.iteration = load_checkpoint(model, optimizer, lr_scheduler, args)
+    else:
+        args.iteration = 0
+
+    return model, optimizer, lr_scheduler
+
+
+def backward_step(optimizer, model, loss, args, timers):
+    """Backward step."""
+
+    # Backward pass.
+    optimizer.zero_grad()
+    if args.fp16:
+        optimizer.backward(loss, update_master_grads=False)
+    else:
+        loss.backward()
+
+    # All-reduce if needed.
+    if args.DDP_impl == 'local':
+        timers('allreduce').start()
+        model.allreduce_params(reduce_after=False,
+                               fp32_allreduce=args.fp32_allreduce)
+        timers('allreduce').stop()
+
+    # Update master gradients.
+    if args.fp16:
+        optimizer.update_master_grads()
+
+    # Clipping gradients helps prevent the exploding gradient.
+    if args.clip_grad > 0:
+        if not args.fp16:
+            mpu.clip_grad_norm(model.parameters(), args.clip_grad)
+        else:
+            optimizer.clip_master_grads(args.clip_grad)
+
+
+def train_step(forward_step_func, data_iterator, model, optimizer, lr_scheduler,
+               args, timers):
+    """Single training step."""
+
+    # Forward model for one step.
+    timers('forward').start()
+    loss, loss_reduced = forward_step_func(data_iterator, model, args, timers)
+    timers('forward').stop()
+
+    # Calculate gradients, reduce across processes, and clip.
+    timers('backward').start()
+    backward_step(optimizer, model, loss, args, timers)
+    timers('backward').stop()
+
+    # Update parameters.
+    timers('optimizer').start()
+    optimizer.step()
+    timers('optimizer').stop()
+
+    # Update learning rate.
+    skipped_iter = 0
+    if not (args.fp16 and optimizer.overflow):
+        lr_scheduler.step()
+    else:
+        skipped_iter = 1
+
+    return loss_reduced, skipped_iter
+
+
+def train(forward_step_func, model, optimizer, lr_scheduler,
+          train_data_iterator, val_data_iterator, timers, args, writer):
+    """Train the model function."""
+
+    # Turn on training mode which enables dropout.
+    model.train()
+
+    # Tracking loss.
+    total_loss_dict = {}
+
+    # Iterations.
+    iteration = args.iteration
+    skipped_iters = 0
+
+    timers('interval time').start()
+    report_memory_flag = True
+    while iteration < args.train_iters:
+
+        loss_dict, skipped_iter = train_step(forward_step_func,
+                                             train_data_iterator,
+                                             model,
+                                             optimizer,
+                                             lr_scheduler,
+                                             args, timers)
+        skipped_iters += skipped_iter
+        iteration += 1
+
+        # Update losses.
+        for key in loss_dict:
+            total_loss_dict[key] = total_loss_dict.get(key, 0.) + loss_dict[key]
+
+        # Logging.
+        if args.DDP_impl == 'torch':
+            timers_to_log = ['forward', 'backward', 'optimizer',
+                             'batch generator']
+        else:
+            timers_to_log = ['forward', 'backward', 'allreduce', 'optimizer',
+                             'batch generator']
+
+        learning_rate = optimizer.param_groups[0]['lr']
+
+        if writer and torch.distributed.get_rank() == 0:
+            writer.add_scalar('learning_rate', learning_rate, iteration)
+            for key in total_loss_dict:
+                writer.add_scalar(key, total_loss_dict[key], iteration)
+            if args.fp16:
+                writer.add_scalar('loss_scale', optimizer.loss_scale, iteration)
+            normalizer = iteration % args.log_interval
+            if normalizer == 0:
+                normalizer = args.log_interval
+            timers.write(timers_to_log, writer, iteration,
+                         normalizer=normalizer)
+
+        if iteration % args.log_interval == 0:
+            elapsed_time = timers('interval time').elapsed()
+            if writer and torch.distributed.get_rank() == 0:
+                writer.add_scalar('iteration_time',
+                                  elapsed_time / args.log_interval, iteration)
+            log_string = ' iteration {:8d}/{:8d} |'.format(iteration,
+                                                           args.train_iters)
+            log_string += ' elapsed time per iteration (ms): {:.1f} |'.format(
+                elapsed_time * 1000.0 / args.log_interval)
+            log_string += ' learning rate: {:.3E} |'.format(learning_rate)
+            for key in total_loss_dict:
+                avg = total_loss_dict[key].item() / args.log_interval
+                log_string += ' {}: {:.6E} |'.format(key, avg)
+                total_loss_dict[key] = 0.0
+            if args.fp16:
+                log_string += ' loss scale: {:.1f} |'.format(
+                    optimizer.loss_scale)
+            print_rank_0(log_string)
+            if report_memory_flag:
+                report_memory('after {} iterations'.format(iteration))
+                report_memory_flag = False
+            timers.log(timers_to_log, normalizer=args.log_interval)
+
+        # Autoresume
+        if (iteration % args.adlr_autoresume_interval == 0) and \
+           args.adlr_autoresume:
+            check_adlr_autoresume_termination(iteration, model, optimizer,
+                                              lr_scheduler, args)
+
+        # Checkpointing
+        if args.save and args.save_interval and \
+           iteration % args.save_interval == 0:
+            save_checkpoint(iteration, model, optimizer, lr_scheduler, args)
+
+        # Evaluation
+        if args.eval_interval and iteration % args.eval_interval == 0 and \
+           args.do_valid:
+            prefix = 'iteration {}'.format(iteration)
+            evaluate_and_print_results(prefix, forward_step_func,
+                                       val_data_iterator, model, args,
+                                       writer, iteration, timers, False)
+
+        if args.exit_interval and iteration % args.exit_interval == 0:
+            torch.distributed.barrier()
+            time_str = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
+            rank = torch.distributed.get_rank()
+            print('rank: {} | time: {} | exiting the program at iteration {}'.
+                  format(rank, time_str, iteration), flush=True)
+            exit()
+
+    return iteration, skipped_iters
+
+
+def evaluate(forward_step_func, data_iterator, model,
+             args, timers, verbose=False):
+    """Evaluation."""
+
+    # Turn on evaluation mode which disables dropout.
+    model.eval()
+
+    total_loss_dict = {}
+
+    with torch.no_grad():
+        iteration = 0
+        while iteration < args.eval_iters:
+            iteration += 1
+            if verbose and iteration % args.log_interval == 0:
+                print_rank_0('Evaluating iter {}/{}'.format(iteration,
+                                                            args.eval_iters))
+            # Forward evaluation.
+            _, loss_dict = forward_step_func(data_iterator, model,
+                                             args, timers)
+            # Reduce across processes.
+            for key in loss_dict:
+                total_loss_dict[key] = total_loss_dict.get(key, 0.) + \
+                                       loss_dict[key]
+    # Move model back to the train mode.
+    model.train()
+
+    for key in total_loss_dict:
+        total_loss_dict[key] /= args.eval_iters
+
+    return total_loss_dict
+
+
+def evaluate_and_print_results(prefix, forward_step_func,
+                               data_iterator, model,
+                               args, writer, iteration,
+                               timers, verbose=False):
+    """Helper function to evaluate and dump results on screen."""
+    total_loss_dict = evaluate(forward_step_func, data_iterator, model,
+                               args, timers, verbose)
+    string = ' validation loss at {} | '.format(prefix)
+    for key in total_loss_dict:
+        string += '{} value: {:.6E} | '.format(key, total_loss_dict[key].item())
+        ppl = math.exp(min(20, total_loss_dict[key].item()))
+        string += '{} PPL: {:.6E} | '.format(key, ppl)
+        if writer and torch.distributed.get_rank() == 0:
+            writer.add_scalar('{} value'.format(key),
+                              total_loss_dict[key].item(),
+                              iteration)
+            writer.add_scalar('{} ppl'.format(key), ppl, iteration)
+
+    length = len(string) + 1
+    print_rank_0('-' * length)
+    print_rank_0(string)
+    print_rank_0('-' * length)
+
+
+def get_train_val_test_data_iterators(train_data, val_data, test_data, args):
+    """Build train/validation/test iterators"""
+
+    # If resume is on, shift the start iterations.
+    if args.resume_dataloader:
+        if train_data is not None:
+            train_data.batch_sampler.start_iter = args.iteration % \
+                                                  len(train_data)
+            print_rank_0('setting training data start iteration to {}'.
+                         format(train_data.batch_sampler.start_iter))
+        if val_data is not None:
+            start_iter_val = (args.iteration // args.eval_interval) * \
+                             args.eval_iters
+            val_data.batch_sampler.start_iter = start_iter_val % \
+                                                len(val_data)
+            print_rank_0('setting validation data start iteration to {}'.
+                         format(val_data.batch_sampler.start_iter))
+
+    if train_data is not None:
+        train_data_iterator = iter(train_data)
+    else:
+        train_data_iterator = None
+
+    if val_data is not None:
+        val_data_iterator = iter(val_data)
+    else:
+        val_data_iterator = None
+
+    if test_data is not None:
+        test_data_iterator = iter(test_data)
+    else:
+        test_data_iterator = None
+
+    return train_data_iterator, val_data_iterator, test_data_iterator

megatron/utils.py

@@ -20,12 +20,29 @@ import random
 import time
 import numpy as np
 import torch
-
 from torch.nn.parallel.distributed import DistributedDataParallel as torchDDP
-from megatron.model import DistributedDataParallel as LocalDDP
-from megatron.fp16 import FP16_Optimizer
+
+from apex.optimizers import FusedAdam as Adam
+
 from megatron import mpu
-from megatron import model
+from megatron.fp16 import FP16_Module
+from megatron.fp16 import FP16_Optimizer
+from megatron.model import DistributedDataParallel as LocalDDP
+from megatron.model import get_params_for_weight_decay_optimization
+
+
+def get_tensorboard_writer(args):
+    writer = None
+    if args.tensorboard_dir and args.rank == 0:
+        try:
+            from torch.utils.tensorboard import SummaryWriter
+            writer = SummaryWriter(log_dir=args.tensorboard_dir)
+        except ModuleNotFoundError:
+            print_rank_0('WARNING: TensorBoard writing requested but is not '
+                         'available (are you using PyTorch 1.1.0 or later?), '
+                         'no TensorBoard logs will be written.')
+            writer = None
+    return writer
 
 
 def print_rank_0(message):
@@ -39,12 +56,12 @@ def print_rank_0(message):
 def enable_adlr_autoresume(args):
     print_rank_0('enabling autoresume ...')
     import sys
-    sys.path.append(os.environ.get('SUBMIT_SCRIPTS','.'))
+    sys.path.append(os.environ.get('SUBMIT_SCRIPTS', '.'))
     try:
         from userlib.auto_resume import AutoResume
     except:
         print_rank_0('ADLR autoresume is not available, exiting ...')
-        exit(0)
+        exit()
     args.AutoResume = AutoResume
     args.AutoResume.init()
 
@@ -74,6 +91,7 @@ def print_args(args, writer=None):
         if writer:
             writer.add_text(arg, str(getattr(args, arg)))
 
+
 def print_params_min_max_norm(optimizer, iteration):
     """Print min, max, and norm of all parameters."""
     index = 0
@@ -220,24 +238,6 @@ def initialize_distributed(args):
     mpu.initialize_model_parallel(args.model_parallel_size)
 
 
-def wrap_model_for_distributed_training(model, args):
-    """Wrap model for distributed training."""
-    if args.DDP_impl == 'torch':
-        i = torch.cuda.current_device()
-        args.DDP_type = torchDDP
-        model = args.DDP_type(model, device_ids=[i], output_device=i,
-                              process_group=mpu.get_data_parallel_group())
-        return model
-    elif args.DDP_impl == 'local':
-        args.DDP_type = LocalDDP
-        model = args.DDP_type(model)
-        return model
-    else:
-        print_rank_0('Unknown DDP implementation specified: {}. '
-                     'Exiting.'.format(args.DDP_impl))
-        exit()
-
-
 def set_random_seed(seed):
     """Set random seed for reproducability."""
 
@@ -284,7 +284,7 @@ def save_checkpoint(iteration, model, optimizer,
 
         sd = {}
         sd['iteration'] = iteration
-        sd['model'] = model.state_dict()
+        sd['model'] = model.state_dict_for_save_checkpoint()
 
         # Optimizer stuff.
         if not args.no_save_optim:
@@ -378,7 +378,6 @@ def load_checkpoint(model, optimizer, lr_scheduler, args):
                 print_rank_0('A metadata file exists but Unable to load iteration '
                              ' from checkpoint {}, exiting'.format(checkpoint_name))
                 exit()
-
     # Model.
     try:
         model.load_state_dict(sd['model'])
@@ -410,7 +409,7 @@ def load_checkpoint(model, optimizer, lr_scheduler, args):
             torch.cuda.set_rng_state(sd['cuda_rng_state'])
             mpu.get_cuda_rng_tracker().set_states(sd['rng_tracker_states'])
         except KeyError:
-            print_rank_0('Unable to load optimizer from checkpoint {}, exiting. '
+            print_rank_0('Unable to load optimizer from checkpoint {}, exiting.'
                          'Specify --no-load-optim or --finetune to prevent '
                          'attempting to load the optimizer '
                          'state.'.format(checkpoint_name))
@@ -422,6 +421,7 @@ def load_checkpoint(model, optimizer, lr_scheduler, args):
 
     return iteration
 
+
 def load_weights(src, dst, dst2src=False):
     """
     Loads weights from src to dst via in place copy.

pretrain_bert.py

@@ -15,166 +15,43 @@
 
 """Pretrain BERT"""
 
-from datetime import datetime
-import os
-import random
-import numpy as np
 import torch
 import torch.nn.functional as F
 
-from arguments import get_args
 from configure_data import configure_data
-from megatron.fp16 import FP16_Module
-from megatron.fp16 import FP16_Optimizer
-from megatron.learning_rates import AnnealingLR
-from megatron.model import BertModel
-from megatron.model import get_params_for_weight_decay_optimization
-from megatron.model import gpt2_get_params_for_weight_decay_optimization
 from megatron import mpu
-from apex.optimizers import FusedAdam as Adam
-from megatron.utils import Timers
-from megatron.utils import save_checkpoint
-from megatron.utils import load_checkpoint
-from megatron.utils import report_memory
-from megatron.utils import print_args
-from megatron.utils import print_params_min_max_norm
+from megatron.model import BertModel
 from megatron.utils import print_rank_0
-from megatron.utils import enable_adlr_autoresume
-from megatron.utils import check_adlr_autoresume_termination
-from megatron.utils import initialize_distributed
-from megatron.utils import set_random_seed
-from megatron.utils import wrap_model_for_distributed_training
 from megatron.utils import vocab_size_with_padding
+from megatron.training import run
+
 
-def get_model(args):
+def model_provider(args):
     """Build the model."""
 
     print_rank_0('building BERT model ...')
-    model = BertModel(args)
-
-    if mpu.get_data_parallel_rank() == 0:
-        print(' > number of parameters on model parallel rank {}: {}'.format(
-            mpu.get_model_parallel_rank(),
-            sum([p.nelement() for p in model.parameters()])), flush=True)
-
-    # GPU allocation.
-    model.cuda(torch.cuda.current_device())
-
-    # Fp16 conversion.
-    if args.fp16:
-        model = FP16_Module(model)
-        if args.fp32_embedding:
-            model.module.model.bert.embeddings.word_embeddings.float()
-            model.module.model.bert.embeddings.position_embeddings.float()
-            model.module.model.bert.embeddings.token_type_embeddings.float()
-        if args.fp32_tokentypes:
-            model.module.model.bert.embeddings.token_type_embeddings.float()
-        if args.fp32_layernorm:
-            for name, _module in model.named_modules():
-                if 'LayerNorm' in name:
-                    _module.float()
-
-    # Wrap model for distributed training.
-    model = wrap_model_for_distributed_training(model, args)
-
-    return model
 
+    model = BertModel(
+        num_layers=args.num_layers,
+        vocab_size=args.vocab_size,
+        hidden_size=args.hidden_size,
+        num_attention_heads=args.num_attention_heads,
+        embedding_dropout_prob=args.hidden_dropout,
+        attention_dropout_prob=args.attention_dropout,
+        output_dropout_prob=args.hidden_dropout,
+        max_sequence_length=args.max_position_embeddings,
+        checkpoint_activations=args.checkpoint_activations,
+        checkpoint_num_layers=args.checkpoint_num_layers,
+        add_binary_head=True,
+        layernorm_epsilon=args.layernorm_epsilon,
+        num_tokentypes=args.tokentype_size,
+        parallel_output=True)
 
-def get_optimizer(model, args):
-    """Set up the optimizer."""
-
-    # Build parameter groups (weight decay and non-decay).
-    while isinstance(model, (args.DDP_type, FP16_Module)):
-        model = model.module
-    layers = model.model.bert.encoder.layer
-    pooler = model.model.bert.pooler
-    lmheads = model.model.cls.predictions
-    nspheads = model.model.cls.seq_relationship
-    embeddings = model.model.bert.embeddings
-    param_groups = []
-    param_groups += list(get_params_for_weight_decay_optimization(layers))
-    param_groups += list(get_params_for_weight_decay_optimization(pooler))
-    param_groups += list(get_params_for_weight_decay_optimization(nspheads))
-    param_groups += list(get_params_for_weight_decay_optimization(embeddings))
-    param_groups += list(get_params_for_weight_decay_optimization(
-        lmheads.transform))
-    param_groups[1]['params'].append(lmheads.bias)
-
-    # Add model parallel attribute if it is not set.
-    for param_group in param_groups:
-        for param in param_group['params']:
-            if not hasattr(param, 'model_parallel'):
-                param.model_parallel = False
-
-    # Use Adam.
-    betas = (0.9, 0.999)
-    optimizer = Adam(param_groups, betas=betas,
-                     lr=args.lr, weight_decay=args.weight_decay)
-
-    # Wrap into fp16 optimizer.
-    if args.fp16:
-        optimizer = FP16_Optimizer(optimizer,
-                                   static_loss_scale=args.loss_scale,
-                                   dynamic_loss_scale=args.dynamic_loss_scale,
-                                   dynamic_loss_args={
-                                       'scale_window': args.loss_scale_window,
-                                       'min_scale':args.min_scale,
-                                       'delayed_shift': args.hysteresis})
-
-    return optimizer
-
-
-def get_learning_rate_scheduler(optimizer, args):
-    """Build the learning rate scheduler."""
-
-    # Add linear learning rate scheduler.
-    if args.lr_decay_iters is not None:
-        num_iters = args.lr_decay_iters
-    else:
-        num_iters = args.train_iters
-    init_step = -1
-    warmup_iter = args.warmup * num_iters
-    lr_scheduler = AnnealingLR(optimizer,
-                               start_lr=args.lr,
-                               warmup_iter=warmup_iter,
-                               num_iters=num_iters,
-                               decay_style=args.lr_decay_style,
-                               last_iter=init_step,
-                               min_lr=args.min_lr,
-                               use_checkpoint_lr_scheduler=args.use_checkpoint_lr_scheduler,
-                               override_lr_scheduler=args.override_lr_scheduler)
-
-    return lr_scheduler
-
-
-def setup_model_and_optimizer(args):
-    """Setup model and optimizer."""
-
-    model = get_model(args)
-    optimizer = get_optimizer(model, args)
-    lr_scheduler = get_learning_rate_scheduler(optimizer, args)
-
-    if args.load is not None:
-        args.iteration = load_checkpoint(model, optimizer, lr_scheduler, args)
-    else:
-        args.iteration = 0
-
-    return model, optimizer, lr_scheduler
+    return model
 
 
 def get_batch(data_iterator, timers):
-    ''' get_batch subdivides the source data into chunks of
-    length args.seq_length. If source is equal to the example
-    output of the data loading example, with a seq_length limit
-    of 2, we'd get the following two Variables for i = 0:
-    ┌ a g m s ┐ ┌ b h n t ┐
-    └ b h n t ┘ └ c i o u ┘
-    Note that despite the name of the function, the subdivison of data is not
-    done along the batch dimension (i.e. dimension 1), since that was handled
-    by the data loader. The chunks are along dimension 0, corresponding
-    to the seq_len dimension in the LSTM. A Variable representing an appropriate
-    shard reset mask of the same dimensions is also returned.
-    '''
+
     # Items and their type.
     keys = ['text', 'types', 'is_random', 'mask', 'mask_labels', 'pad_mask']
     datatype = torch.int64
@@ -204,266 +81,32 @@ def forward_step(data_iterator, model, args, timers):
 
     # Get the batch.
     timers('batch generator').start()
-    tokens, types, next_sentence, loss_mask, lm_labels, \
-        padding_mask = get_batch(data_iterator, timers)
+    tokens, types, next_sentence, loss_mask, lm_labels, padding_mask \
+        = get_batch(data_iterator, timers)
     timers('batch generator').stop()
+
     # Forward model.
-    output, nsp = model(tokens, types, 1-padding_mask,
-                        checkpoint_activations=args.checkpoint_activations)
+    lm_logits, nsp_logits = model(tokens, 1-padding_mask, tokentype_ids=types)
 
-    nsp_loss = F.cross_entropy(nsp.view(-1, 2).contiguous().float(),
+    nsp_loss = F.cross_entropy(nsp_logits.view(-1, 2).contiguous().float(),
                                next_sentence.view(-1).contiguous(),
                                ignore_index=-1)
 
-    losses = mpu.vocab_parallel_cross_entropy(
-        output.contiguous().float(), lm_labels.contiguous())
-    loss_mask = loss_mask.contiguous()
+    lm_loss_ = mpu.vocab_parallel_cross_entropy(lm_logits.contiguous().float(),
+                                                lm_labels.contiguous())
     lm_loss = torch.sum(
-        losses.view(-1) * loss_mask.view(-1).float()) / loss_mask.sum()
+        lm_loss_.view(-1) * loss_mask.reshape(-1)) / loss_mask.sum()
 
-    return lm_loss, nsp_loss
-
-
-def backward_step(optimizer, model, lm_loss, nsp_loss, args, timers):
-    """Backward step."""
-
-    # Total loss.
     loss = lm_loss + nsp_loss
 
-    # Backward pass.
-    optimizer.zero_grad()
-    if args.fp16:
-        optimizer.backward(loss, update_master_grads=False)
-    else:
-        loss.backward()
-
-    # Reduce across processes.
-    lm_loss_reduced = lm_loss
-    nsp_loss_reduced = nsp_loss
-
-    reduced_losses = torch.cat((lm_loss.view(1), nsp_loss.view(1)))
-    torch.distributed.all_reduce(reduced_losses.data)
-    reduced_losses.data = reduced_losses.data / args.world_size
-    if args.DDP_impl == 'local':
-        timers('allreduce').start()
-        model.allreduce_params(reduce_after=False,
-                               fp32_allreduce=args.fp32_allreduce)
-        timers('allreduce').stop()
+    reduced_losses = torch.cat((lm_loss.clone().detach().view(1),
+                                nsp_loss.clone().detach().view(1)))
+    torch.distributed.all_reduce(reduced_losses)
+    reduced_losses = reduced_losses / torch.distributed.get_world_size()
     lm_loss_reduced = reduced_losses[0]
     nsp_loss_reduced = reduced_losses[1]
 
-    # Update master gradients.
-    if args.fp16:
-        optimizer.update_master_grads()
-
-    # Clipping gradients helps prevent the exploding gradient.
-    if args.clip_grad > 0:
-        if not args.fp16:
-            mpu.clip_grad_norm(model.parameters(), args.clip_grad)
-        else:
-            optimizer.clip_master_grads(args.clip_grad)
-
-    return lm_loss_reduced, nsp_loss_reduced
-
-
-def train_step(data_iterator, model, optimizer, lr_scheduler,
-               args, timers):
-    """Single training step."""
-
-    # Forward model for one step.
-    timers('forward').start()
-    lm_loss, nsp_loss = forward_step(data_iterator, model,
-                                     args, timers)
-    timers('forward').stop()
-
-    # Calculate gradients, reduce across processes, and clip.
-    timers('backward').start()
-    lm_loss_reduced, nsp_loss_reduced = backward_step(optimizer, model, lm_loss,
-                                                      nsp_loss, args, timers)
-    timers('backward').stop()
-
-    # Update parameters.
-    timers('optimizer').start()
-    optimizer.step()
-    timers('optimizer').stop()
-
-    # Update learning rate.
-    skipped_iter = 0
-    if not (args.fp16 and optimizer.overflow):
-        lr_scheduler.step()
-    else:
-        skipped_iter = 1
-
-    return lm_loss_reduced, nsp_loss_reduced, skipped_iter
-
-
-def train(model, optimizer, lr_scheduler,
-          train_data_iterator, val_data_iterator, timers, args, writer):
-    """Train the model."""
-
-    # Turn on training mode which enables dropout.
-    model.train()
-
-    # Tracking loss.
-    total_lm_loss = 0.0
-    total_nsp_loss = 0.0
-
-    # Iterations.
-    iteration = args.iteration
-    skipped_iters = 0
-
-    timers('interval time').start()
-    report_memory_flag = True
-    while iteration < args.train_iters:
-
-        lm_loss, nsp_loss, skipped_iter = train_step(train_data_iterator,
-                                                     model,
-                                                     optimizer,
-                                                     lr_scheduler,
-                                                     args, timers)
-        skipped_iters += skipped_iter
-        iteration += 1
-
-        # Update losses.
-        current_lm_loss = lm_loss.data.detach().float()
-        current_nsp_loss = nsp_loss.data.detach().float()
-        total_lm_loss += current_lm_loss
-        total_nsp_loss += current_nsp_loss
-
-        # Logging.
-
-        if args.DDP_impl == 'torch':
-            timers_to_log = ['forward', 'backward', 'optimizer',
-                            'batch generator', 'data loader']
-        else:
-            timers_to_log = ['forward', 'backward', 'allreduce', 'optimizer',
-                             'batch generator', 'data loader']
-
-        learning_rate = optimizer.param_groups[0]['lr']
-
-        if writer and args.rank == 0:
-            writer.add_scalar('learning_rate', learning_rate, iteration)
-            writer.add_scalar('lm_loss', current_lm_loss, iteration)
-            writer.add_scalar('nsp_loss', current_nsp_loss, iteration)
-            if args.fp16:
-                writer.add_scalar('loss_scale', optimizer.loss_scale, iteration)
-            normalizer = iteration % args.log_interval
-            if normalizer == 0:
-                normalizer = args.log_interval
-            timers.write(timers_to_log, writer, iteration,
-                         normalizer=normalizer)
-
-        if iteration % args.log_interval == 0:
-            avg_nsp_loss = total_nsp_loss.item() / args.log_interval
-            avg_lm_loss = total_lm_loss.item() / args.log_interval
-            elapsed_time = timers('interval time').elapsed()
-            if writer and args.rank == 0:
-                writer.add_scalar('iteration_time',
-                                  elapsed_time / args.log_interval, iteration)
-            log_string = ' iteration {:8d}/{:8d} |'.format(iteration,
-                                                            args.train_iters)
-            log_string += ' elapsed time per iteration (ms): {:.1f} |'.format(
-                elapsed_time * 1000.0 / args.log_interval)
-            log_string += ' learning rate {:.3E} |'.format(learning_rate)
-            log_string += ' lm loss {:.6E} |'.format(avg_lm_loss)
-            log_string += ' nsp loss {:.6E} |'.format(avg_nsp_loss)
-            if args.fp16:
-                log_string += ' loss scale {:.1f} |'.format(
-                    optimizer.loss_scale)
-            print_rank_0(log_string)
-            total_nsp_loss = 0.0
-            total_lm_loss = 0.0
-            if report_memory_flag:
-                report_memory('after {} iterations'.format(iteration))
-                report_memory_flag = False
-            timers.log(timers_to_log, normalizer=args.log_interval)
-
-        # Autoresume
-        if (iteration % args.adlr_autoresume_interval == 0) and args.adlr_autoresume:
-            check_adlr_autoresume_termination(iteration, model, optimizer,
-                                              lr_scheduler, args)
-
-        # Checkpointing
-        if args.save and args.save_interval and iteration % args.save_interval == 0:
-            save_checkpoint(iteration, model, optimizer, lr_scheduler, args)
-
-        # Evaluation
-        if args.eval_interval and iteration % args.eval_interval == 0 and args.do_valid:
-            prefix = 'iteration {}'.format(iteration)
-            evaluate_and_print_results(prefix, val_data_iterator, model, args,
-                                       writer, iteration, timers, False)
-
-        if args.exit_interval and iteration % args.exit_interval == 0:
-            torch.distributed.barrier()
-            time_str = datetime.now().strftime('%Y-%m-%d %H:%M:%S')
-            rank = torch.distributed.get_rank()
-            print('rank: {} | time: {} | exiting the program at iteration {}'.
-                  format(rank, time_str, iteration), flush=True)
-            exit()
-
-    return iteration, skipped_iters
-
-
-def evaluate(data_iterator, model, args, timers, verbose = False):
-    """Evaluation."""
-
-    # Turn on evaluation mode which disables dropout.
-    model.eval()
-
-    total_lm_loss = 0
-    total_nsp_loss = 0
-
-    with torch.no_grad():
-        iteration = 0
-        while iteration < args.eval_iters:
-            iteration += 1
-            if verbose and iteration % args.log_interval == 0:
-                print_rank_0('Evaluating iter {}/{}'.format(iteration, args.eval_iters))
-            # Forward evaluation.
-            lm_loss, nsp_loss = forward_step(data_iterator, model,
-                                             args, timers)
-            # Reduce across processes.
-            if isinstance(model, args.DDP_type):
-                reduced_losses = torch.cat((lm_loss.view(1), nsp_loss.view(1)))
-                torch.distributed.all_reduce(reduced_losses.data)
-                reduced_losses.data = reduced_losses.data/args.world_size
-                lm_loss = reduced_losses[0]
-                nsp_loss = reduced_losses[1]
-
-            total_lm_loss += lm_loss.data.detach().float().item()
-            total_nsp_loss += nsp_loss.data.detach().float().item()
-
-    # Move model back to the train mode.
-    model.train()
-
-    total_lm_loss /= args.eval_iters
-    total_nsp_loss /= args.eval_iters
-    return total_lm_loss, total_nsp_loss
-
-
-def evaluate_and_print_results(prefix, data_iterator, model,
-                               args, writer, iteration,
-                               timers, verbose=False):
-    """Helper function to evaluate and dump results on screen."""
-    lm_loss, nsp_loss = evaluate(data_iterator, model,
-                                 args, timers, verbose)
-    val_loss = lm_loss + nsp_loss
-    print_rank_0('-' * 100)
-    string = ' validation loss at {} | '.format(prefix)
-    string += 'LM loss: {:.6E} | '.format(lm_loss)
-    string += 'NSP loss: {:.6E} | '.format(nsp_loss)
-    string += 'total loss: {:.6E}'.format(val_loss)
-    length = len(string) + 1
-    print_rank_0('-' * length)
-    print_rank_0(string)
-    print_rank_0('-' * length)
-
-    if writer and args.rank == 0:
-        writer.add_scalar('val_lm_loss', lm_loss, iteration)
-        writer.add_scalar('val_nsp_loss', nsp_loss, iteration)
-        writer.add_scalar('val_total_loss', val_loss, iteration)
-
-    return val_loss
+    return loss, {'lm loss': lm_loss_reduced, 'nsp loss': nsp_loss_reduced}
 
 
 def get_train_val_test_data(args):
@@ -497,104 +140,13 @@ def get_train_val_test_data(args):
     args.do_valid = token_counts[3].item()
     args.do_test = token_counts[4].item()
 
-    return train_data, val_data, test_data, num_tokens, num_type_tokens
-
-
-def main():
-    """Main training program."""
-
-    # Disable CuDNN.
-    torch.backends.cudnn.enabled = False
-
-    # Timer.
-    timers = Timers()
-
-    # Arguments.
-    args = get_args()
-
-    writer = None
-    if args.tensorboard_dir and args.rank == 0:
-        try:
-            from torch.utils.tensorboard import SummaryWriter
-            writer = SummaryWriter(log_dir = args.tensorboard_dir)
-        except ModuleNotFoundError:
-            print_rank_0('WARNING: TensorBoard writing requested but is not '
-                         'available (are you using PyTorch 1.1.0 or later?), '
-                         'no TensorBoard logs will be written.')
-            writer = None
-
-    # Pytorch distributed.
-    initialize_distributed(args)
-    if torch.distributed.get_rank() == 0:
-        print('Pretrain BERT model')
-        print_args(args, writer)
-
-    # Autoresume.
-    torch.distributed.barrier()
-    if args.adlr_autoresume:
-        enable_adlr_autoresume(args)
-
-    # Random seeds for reproducability.
-    set_random_seed(args.seed)
-
-    # Data stuff.
-    train_data, val_data, test_data, args.tokenizer_num_tokens, \
-        args.tokenizer_num_type_tokens = get_train_val_test_data(args)
-
-    # Model, optimizer, and learning rate.
-    model, optimizer, lr_scheduler = setup_model_and_optimizer(args)
-
-    if args.resume_dataloader:
-        if train_data is not None:
-            train_data.batch_sampler.start_iter = args.iteration % \
-                                                  len(train_data)
-            print_rank_0('setting training data start iteration to {}'.
-                         format(train_data.batch_sampler.start_iter))
-        if val_data is not None:
-            start_iter_val = (args.iteration // args.eval_interval) * \
-                             args.eval_iters
-            val_data.batch_sampler.start_iter = start_iter_val % \
-                                                len(val_data)
-            print_rank_0('setting validation data start iteration to {}'.
-                         format(val_data.batch_sampler.start_iter))
-
-    if train_data is not None:
-        train_data_iterator = iter(train_data)
-    else:
-        train_data_iterator = None
-    if val_data is not None:
-        val_data_iterator = iter(val_data)
-    else:
-        val_data_iterator = None
-
-    iteration = 0
-    if args.train_iters > 0:
-        if args.do_train:
-            iteration, skipped = train(model, optimizer,
-                                       lr_scheduler,
-                                       train_data_iterator,
-                                       val_data_iterator,
-                                       timers, args, writer)
-        if args.do_valid:
-            prefix = 'the end of training for val data'
-            val_loss = evaluate_and_print_results(prefix, val_data_iterator,
-                                                  model, args, writer, iteration,
-                                                  timers, False)
-
-    if args.save and iteration != 0:
-        save_checkpoint(iteration, model, optimizer, lr_scheduler, args)
-
-    if test_data is not None:
-        test_data_iterator = iter(test_data)
-    else:
-        test_data_iterator = None
+    args.vocab_size = num_tokens
+    args.tokentype_size = num_type_tokens
 
-    if args.do_test:
-        # Run on test data.
-        prefix = 'the end of training for test data'
-        evaluate_and_print_results(prefix, test_data_iterator,
-                                   model, args, None, 0, timers, True)
+    return train_data, val_data, test_data
 
 
 if __name__ == "__main__":
-    main()
+
+    run('Pretrain BERT model', get_train_val_test_data,
+        model_provider, forward_step)