Merge branch 'main_retriver_merge' into 'main'

Merge ICT Retriever with Main branch

See merge request ADLR/megatron-lm!227

examples/pretrain_ict.sh

+#! /bin/bash
+
+# Runs the "217M" parameter biencoder model for ICT retriever
+
+RANK=0
+WORLD_SIZE=1
+
+PRETRAINED_BERT_PATH=<Specify path of pretrained BERT model>
+TEXT_DATA_PATH=<Specify path and file prefix of the text data>
+TITLE_DATA_PATH=<Specify path and file prefix od the titles>
+CHECKPOINT_PATH=<Specify path>
+
+
+python pretrain_ict.py \
+        --num-layers 12 \
+        --hidden-size 768 \
+        --num-attention-heads 12 \
+        --tensor-model-parallel-size 1 \
+        --micro-batch-size 32 \
+        --seq-length 256 \
+        --max-position-embeddings 512 \
+        --train-iters 100000 \
+        --vocab-file bert-vocab.txt \
+        --tokenizer-type BertWordPieceLowerCase \
+        --DDP-impl torch \
+        --bert-load ${PRETRAINED_BERT_PATH} \
+        --log-interval 100 \
+        --eval-interval 1000 \
+        --eval-iters 10 \
+        --retriever-report-topk-accuracies 1 5 10 20 100 \
+        --retriever-score-scaling \
+        --load $CHECKPOINT_PATH \
+        --save $CHECKPOINT_PATH \
+        --data-path ${TEXT_DATA_PATH} \
+        --titles-data-path ${TITLE_DATA_PATH} \
+        --lr 0.0001 \
+        --lr-decay-style linear \
+        --weight-decay 1e-2 \
+        --clip-grad 1.0 \
+        --lr-warmup-fraction 0.01 \
+        --save-interval 4000 \
+        --exit-interval 8000 \
+        --query-in-block-prob 0.1 \
+        --fp16

megatron/arguments.py

@@ -39,7 +39,7 @@ def parse_args(extra_args_provider=None, defaults={},
     parser = _add_validation_args(parser)
     parser = _add_data_args(parser)
     parser = _add_autoresume_args(parser)
-    parser = _add_realm_args(parser)
+    parser = _add_biencoder_args(parser)
     parser = _add_vit_args(parser)
     parser = _add_logging_args(parser)
 
@@ -672,13 +672,19 @@ def _add_autoresume_args(parser):
     return parser
 
 
-def _add_realm_args(parser):
-    group = parser.add_argument_group(title='realm')
+def _add_biencoder_args(parser):
+    group = parser.add_argument_group(title='biencoder')
 
     # network size
     group.add_argument('--ict-head-size', type=int, default=None,
                        help='Size of block embeddings to be used in ICT and '
-                       'REALM (paper default: 128)')
+                        'REALM (paper default: 128)')
+    group.add_argument('--biencoder-projection-dim', type=int, default=0,
+                       help='Size of projection head used in biencoder (paper'
+                        ' default: 128)')
+    group.add_argument('--biencoder-shared-query-context-model', action='store_true',
+                        help='Whether to share the parameters of the query '
+                        'and context models or not')
 
     # checkpointing
     group.add_argument('--ict-load', type=str, default=None,
@@ -697,8 +703,12 @@ def _add_realm_args(parser):
                        help='Whether to use one sentence documents in ICT')
 
     # training
-    group.add_argument('--report-topk-accuracies', nargs='+', default=[],
-                       help="Which top-k accuracies to report (e.g. '1 5 20')")
+    group.add_argument('--retriever-report-topk-accuracies', nargs='+', type=int,
+                        default=[], help="Which top-k accuracies to report "
+                        "(e.g. '1 5 20')")
+    group.add_argument('--retriever-score-scaling', action='store_true',
+                       help='Whether to scale retriever scores by inverse '
+                        'square root of hidden size')
 
     # faiss index
     group.add_argument('--faiss-use-gpu', action='store_true',

megatron/checkpointing.py

@@ -206,6 +206,33 @@ def _transpose_first_dim(t, num_splits, num_splits_first, model):
 
     return t
 
+def fix_query_key_value_ordering(model, checkpoint_version):
+    """Fix up query/key/value matrix ordering if checkpoint
+    version is smaller than 2.0
+    """
+    if checkpoint_version < 2.0:
+        for name, param in model.named_parameters():
+            if name.endswith(('.query_key_value.weight', '.query_key_value.bias')):
+                if checkpoint_version == 0:
+                    fixed_param = _transpose_first_dim(param.data, 3, True, model)
+                elif checkpoint_version == 1.0:
+                    fixed_param = _transpose_first_dim(param.data, 3, False, model)
+                else:
+                    print_rank_0(f"Invalid checkpoint version {checkpoint_version}.")
+                    sys.exit()
+                param.data.copy_(fixed_param)
+            if name.endswith(('.key_value.weight', '.key_value.bias')):
+                if checkpoint_version == 0:
+                    fixed_param = _transpose_first_dim(param.data, 2, True, model)
+                elif checkpoint_version == 1.0:
+                    fixed_param = _transpose_first_dim(param.data, 2, False, model)
+                else:
+                    print_rank_0(f"Invalid checkpoint version {checkpoint_version}.")
+                    sys.exit()
+                param.data.copy_(fixed_param)
+        print_rank_0(" succesfully fixed query-key-values ordering for"
+                    " checkpoint version {}".format(checkpoint_version))
+
 def load_checkpoint(model, optimizer, lr_scheduler, load_arg='load', strict=True):
     """Load a model checkpoint and return the iteration.
     strict (bool): whether to strictly enforce that the keys in
@@ -308,28 +335,10 @@ def load_checkpoint(model, optimizer, lr_scheduler, load_arg='load', strict=True
             mpu.set_virtual_pipeline_model_parallel_rank(i)
             model[i].load_state_dict(state_dict['model%d' % i], strict=strict)
 
-    # Fix up query/key/value matrix ordering
-    if get_checkpoint_version() < 2.0:
-        checkpoint_version = get_checkpoint_version()
-        for name, param in model.named_parameters():
-            if name.endswith(('.query_key_value.weight', '.query_key_value.bias')):
-                if checkpoint_version == 0:
-                    fixed_param = _transpose_first_dim(param.data, 3, True, model)
-                elif checkpoint_version == 1.0:
-                    fixed_param = _transpose_first_dim(param.data, 3, False, model)
-                else:
-                    print_rank_0(f"Invalid checkpoint version {checkpoint_version}.")
-                    sys.exit()
-                param.data.copy_(fixed_param)
-            if name.endswith(('.key_value.weight', '.key_value.bias')):
-                if checkpoint_version == 0:
-                    fixed_param = _transpose_first_dim(param.data, 2, True, model)
-                elif checkpoint_version == 1.0:
-                    fixed_param = _transpose_first_dim(param.data, 2, False, model)
-                else:
-                    print_rank_0(f"Invalid checkpoint version {checkpoint_version}.")
-                    sys.exit()
-                param.data.copy_(fixed_param)
+    # Fix up query/key/value matrix ordering if needed
+    checkpoint_version = get_checkpoint_version()
+    print_rank_0(f' checkpoint version {checkpoint_version}')
+    fix_query_key_value_ordering(model, checkpoint_version)
 
     # Optimizer.
     if not release and not args.finetune and not args.no_load_optim:

megatron/data/biencoder_dataset_utils.py

+import os
+import time
+
+import numpy as np
+import torch
+
+from megatron import mpu, print_rank_0
+from megatron.data.dataset_utils import create_masked_lm_predictions, pad_and_convert_to_numpy
+from megatron import get_args, get_tokenizer, print_rank_0, mpu
+
+
+def get_ict_batch(data_iterator):
+    # Items and their type.
+    keys = ['query_tokens', 'query_mask',
+            'context_tokens', 'context_mask', 'block_data']
+    datatype = torch.int64
+
+    # Broadcast data.
+    if data_iterator is None:
+        data = None
+    else:
+        data = next(data_iterator)
+    data_b = mpu.broadcast_data(keys, data, datatype)
+
+    # Unpack.
+    query_tokens = data_b['query_tokens'].long()
+    query_mask = data_b['query_mask'] < 0.5
+    context_tokens = data_b['context_tokens'].long()
+    context_mask = data_b['context_mask'] < 0.5
+    block_indices = data_b['block_data'].long()
+
+    return query_tokens, query_mask,\
+           context_tokens, context_mask, block_indices
+
+
+def join_str_list(str_list):
+    """Join a list of strings, handling spaces appropriately"""
+    result = ""
+    for s in str_list:
+        if s.startswith("##"):
+            result += s[2:]
+        else:
+            result += " " + s
+    return result
+
+
+class BlockSampleData(object):
+    """A struct for fully describing a fixed-size block of data as used in REALM
+
+    :param start_idx: for first sentence of the block
+    :param end_idx: for last sentence of the block (may be partially truncated in sample construction)
+    :param doc_idx: the index of the document from which the block comes in the original indexed dataset
+    :param block_idx: a unique integer identifier given to every block.
+    """
+    def __init__(self, start_idx, end_idx, doc_idx, block_idx):
+        self.start_idx = start_idx
+        self.end_idx = end_idx
+        self.doc_idx = doc_idx
+        self.block_idx = block_idx
+
+    def as_array(self):
+        return np.array([self.start_idx, self.end_idx, self.doc_idx, self.block_idx]).astype(np.int64)
+
+    def as_tuple(self):
+        return self.start_idx, self.end_idx, self.doc_idx, self.block_idx
+
+
+class BlockSamplesMapping(object):
+    def __init__(self, mapping_array):
+        # make sure that the array is compatible with BlockSampleData
+        assert mapping_array.shape[1] == 4
+        self.mapping_array = mapping_array
+
+    def __len__(self):
+        return self.mapping_array.shape[0]
+
+    def __getitem__(self, idx):
+        """Get the data associated with an indexed sample."""
+        sample_data = BlockSampleData(*self.mapping_array[idx])
+        return sample_data
+
+
+def get_block_samples_mapping(block_dataset, title_dataset, data_prefix, num_epochs,
+                              max_num_samples, max_seq_length, seed, name, use_one_sent_docs=False):
+    """Get samples mapping for a dataset over fixed size blocks. This function also requires
+    a dataset of the titles for the source documents since their lengths must be taken into account.
+
+    :return: samples_mapping (BlockSamplesMapping)
+    """
+
+    if not num_epochs:
+        if not max_num_samples:
+            raise ValueError("Need to specify either max_num_samples "
+                             "or num_epochs")
+        num_epochs = np.iinfo(np.int32).max - 1
+    if not max_num_samples:
+        max_num_samples = np.iinfo(np.int64).max - 1
+
+    # Filename of the index mapping
+    indexmap_filename = data_prefix
+    indexmap_filename += '_{}_indexmap'.format(name)
+    if num_epochs != (np.iinfo(np.int32).max - 1):
+        indexmap_filename += '_{}ep'.format(num_epochs)
+    if max_num_samples != (np.iinfo(np.int64).max - 1):
+        indexmap_filename += '_{}mns'.format(max_num_samples)
+    indexmap_filename += '_{}msl'.format(max_seq_length)
+    indexmap_filename += '_{}s'.format(seed)
+    if use_one_sent_docs:
+        indexmap_filename += '_1sentok'
+    indexmap_filename += '.npy'
+
+    # Build the indexed mapping if not exist.
+    if mpu.get_data_parallel_rank() == 0 and \
+            not os.path.isfile(indexmap_filename):
+        print(' > WARNING: could not find index map file {}, building '
+              'the indices on rank 0 ...'.format(indexmap_filename))
+
+        # Make sure the types match the helpers input types.
+        assert block_dataset.doc_idx.dtype == np.int64
+        assert block_dataset.sizes.dtype == np.int32
+
+        # Build samples mapping
+        verbose = torch.distributed.get_rank() == 0
+        start_time = time.time()
+        print_rank_0(' > building samples index mapping for {} ...'.format(
+            name))
+
+        from megatron.data import helpers
+        mapping_array = helpers.build_blocks_mapping(
+            block_dataset.doc_idx,
+            block_dataset.sizes,
+            title_dataset.sizes,
+            num_epochs,
+            max_num_samples,
+            max_seq_length - 3,  # account for added tokens
+            seed,
+            verbose,
+            use_one_sent_docs)
+
+
+        print_rank_0(' > done building samples index mapping')
+        np.save(indexmap_filename, mapping_array, allow_pickle=True)
+        print_rank_0(' > saved the index mapping in {}'.format(
+            indexmap_filename))
+        # Make sure all the ranks have built the mapping
+        print_rank_0(' > elapsed time to build and save samples mapping '
+                     '(seconds): {:4f}'.format(
+            time.time() - start_time))
+
+    # This should be a barrier but nccl barrier assumes
+    # device_index=rank which is not the case for model
+    # parallel case
+    counts = torch.cuda.LongTensor([1])
+    torch.distributed.all_reduce(counts, group=mpu.get_data_parallel_group())
+    assert counts[0].item() == torch.distributed.get_world_size(
+        group=mpu.get_data_parallel_group())
+
+    # Load indexed dataset.
+    print_rank_0(' > loading indexed mapping from {}'.format(
+        indexmap_filename))
+    start_time = time.time()
+
+    mapping_array = np.load(indexmap_filename, allow_pickle=True, mmap_mode='r')
+    samples_mapping = BlockSamplesMapping(mapping_array)
+
+    print_rank_0('    loaded indexed file in {:3.3f} seconds'.format(
+        time.time() - start_time))
+    print_rank_0('    total number of samples: {}'.format(
+        mapping_array.shape[0]))
+
+    return samples_mapping

megatron/data/ict_dataset.py

@@ -9,6 +9,16 @@ from megatron import get_args
 from megatron.data.dataset_utils import get_indexed_dataset_
 from megatron.data.realm_dataset_utils import get_block_samples_mapping
 
+def make_attention_mask(source_block, target_block):
+    """
+    Returns a 2-dimensional (2-D) attention mask
+    :param source_block: 1-D array
+    :param target_block: 1-D array
+    """
+    mask = (target_block[None, :] >= 1) * (source_block[:, None] >= 1)
+    mask = mask.astype(np.int64)
+    # (source_length, target_length)
+    return mask
 
 def get_ict_dataset(use_titles=True, query_in_block_prob=1):
     """Get a dataset which uses block samples mappings to get ICT/block indexing data (via get_block())
@@ -39,7 +49,7 @@ class ICTDataset(Dataset):
     """Dataset containing sentences and their blocks for an inverse cloze task."""
     def __init__(self, name, block_dataset, title_dataset, data_prefix,
                  num_epochs, max_num_samples, max_seq_length, query_in_block_prob,
-                 seed, use_titles=True, use_one_sent_docs=False):
+                 seed, use_titles=True, use_one_sent_docs=False, binary_head=False):
         self.name = name
         self.seed = seed
         self.max_seq_length = max_seq_length
@@ -93,14 +103,20 @@ class ICTDataset(Dataset):
         block = list(itertools.chain(*block))[:self.max_seq_length - title_pad_offset]
 
         query_tokens, query_pad_mask = self.concat_and_pad_tokens(query)
-        block_tokens, block_pad_mask = self.concat_and_pad_tokens(block, title)
+        context_tokens, context_pad_mask = self.concat_and_pad_tokens(block, title)
+
+        query_mask = make_attention_mask(query_tokens, query_tokens)
+        context_mask = make_attention_mask(context_tokens, context_tokens)
+
         block_data = sample_data.as_array()
 
         sample = {
             'query_tokens': query_tokens,
+            'query_mask': query_mask,
             'query_pad_mask': query_pad_mask,
-            'block_tokens': block_tokens,
-            'block_pad_mask': block_pad_mask,
+            'context_tokens': context_tokens,
+            'context_mask': context_mask,
+            'context_pad_mask': context_pad_mask,
             'block_data': block_data,
         }
 

megatron/model/biencoder_model.py

+import os
+import torch
+import sys
+
+from megatron import get_args, print_rank_0
+from megatron.checkpointing import fix_query_key_value_ordering
+from megatron.checkpointing import get_checkpoint_tracker_filename
+from megatron.checkpointing import get_checkpoint_name
+from megatron import mpu, get_tokenizer
+from megatron.model.bert_model import bert_position_ids
+from megatron.model.enums import AttnMaskType
+from megatron.model.language_model import get_language_model
+from megatron.model.utils import get_linear_layer
+from megatron.model.utils import init_method_normal
+from megatron.model.utils import scaled_init_method_normal
+from .module import MegatronModule
+
+def biencoder_model_provider(only_query_model=False,
+                             only_context_model=False,
+                             biencoder_shared_query_context_model=False):
+    """Build the model."""
+    args = get_args()
+
+    assert mpu.get_tensor_model_parallel_world_size() == 1 and \
+        mpu.get_pipeline_model_parallel_world_size() == 1, \
+        "Model parallel size > 1 not supported for ICT"
+
+    print_rank_0('building BiEncoderModel...')
+
+    # simpler to just keep using 2 tokentypes since
+    # the LM we initialize with has 2 tokentypes
+    model = BiEncoderModel(
+        num_tokentypes=2,
+        parallel_output=False,
+        only_query_model=only_query_model,
+        only_context_model=only_context_model,
+        biencoder_shared_query_context_model=\
+            biencoder_shared_query_context_model)
+
+    return model
+
+
+class BiEncoderModel(MegatronModule):
+    """Bert-based module for Biencoder model."""
+
+    def __init__(self,
+                 num_tokentypes=1,
+                 parallel_output=True,
+                 only_query_model=False,
+                 only_context_model=False,
+                 biencoder_shared_query_context_model=False):
+        super(BiEncoderModel, self).__init__()
+        args = get_args()
+
+        bert_kwargs = dict(
+            num_tokentypes=num_tokentypes,
+            parallel_output=parallel_output)
+
+        self.biencoder_shared_query_context_model = \
+            biencoder_shared_query_context_model
+        assert not (only_context_model and only_query_model)
+        self.use_context_model = not only_query_model
+        self.use_query_model = not only_context_model
+        self.biencoder_projection_dim = args.biencoder_projection_dim
+
+        if self.biencoder_shared_query_context_model:
+            self.model = PretrainedBertModel(**bert_kwargs)
+            self._model_key = 'shared_model'
+            self.query_model, self.context_model = self.model, self.model
+        else:
+            if self.use_query_model:
+                # this model embeds (pseudo-)queries - Embed_input in the paper
+                self.query_model = PretrainedBertModel(**bert_kwargs)
+                self._query_key = 'query_model'
+
+            if self.use_context_model:
+                # this model embeds evidence blocks - Embed_doc in the paper
+                self.context_model = PretrainedBertModel(**bert_kwargs)
+                self._context_key = 'context_model'
+
+    def forward(self, query_tokens, query_attention_mask, query_types,
+                context_tokens, context_attention_mask, context_types):
+        """Run a forward pass for each of the models and
+        return the respective embeddings."""
+
+        if self.use_query_model:
+            query_logits = self.embed_text(self.query_model,
+                                           query_tokens,
+                                           query_attention_mask,
+                                           query_types)
+        else:
+            raise ValueError("Cannot embed query without the query model.")
+        if self.use_context_model:
+            context_logits = self.embed_text(self.context_model,
+                                             context_tokens,
+                                             context_attention_mask,
+                                             context_types)
+        else:
+            raise ValueError("Cannot embed block without the block model.")
+        return query_logits, context_logits
+
+    @staticmethod
+    def embed_text(model, tokens, attention_mask, token_types):
+        """Embed a batch of tokens using the model"""
+        logits = model(tokens,
+                              attention_mask,
+                              token_types)
+        return logits
+
+    def state_dict_for_save_checkpoint(self, destination=None, \
+        prefix='', keep_vars=False):
+        """Save dict with state dicts of each of the models."""
+        state_dict_ = {}
+        if self.biencoder_shared_query_context_model:
+            state_dict_[self._model_key] = \
+                self.model.state_dict_for_save_checkpoint(destination,
+                                                          prefix,
+                                                          keep_vars)
+        else:
+            if self.use_query_model:
+                state_dict_[self._query_key] = \
+                    self.query_model.state_dict_for_save_checkpoint(
+                        destination, prefix, keep_vars)
+
+            if self.use_context_model:
+                state_dict_[self._context_key] = \
+                    self.context_model.state_dict_for_save_checkpoint(
+                        destination, prefix, keep_vars)
+
+        return state_dict_
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Load the state dicts of each of the models"""
+        if self.biencoder_shared_query_context_model:
+            print_rank_0("Loading shared query-context model")
+            self.model.load_state_dict(state_dict[self._model_key], \
+                strict=strict)
+        else:
+            if self.use_query_model:
+                print_rank_0("Loading query model")
+                self.query_model.load_state_dict( \
+                    state_dict[self._query_key], strict=strict)
+
+            if self.use_context_model:
+                print_rank_0("Loading context model")
+                self.context_model.load_state_dict( \
+                    state_dict[self._context_key], strict=strict)
+
+    def init_state_dict_from_bert(self):
+        """Initialize the state from a pretrained BERT model
+        on iteration zero of ICT pretraining"""
+        args = get_args()
+
+        if args.bert_load is None:
+            print_rank_0("bert-load argument is None")
+            return
+
+        tracker_filename = get_checkpoint_tracker_filename(args.bert_load)
+        if not os.path.isfile(tracker_filename):
+            raise FileNotFoundError("Could not find BERT checkpoint")
+        with open(tracker_filename, 'r') as f:
+            iteration = int(f.read().strip())
+            assert iteration > 0
+
+        checkpoint_name = get_checkpoint_name(args.bert_load, iteration, False)
+        if mpu.get_data_parallel_rank() == 0:
+            print('global rank {} is loading BERT checkpoint {}'.format(
+                torch.distributed.get_rank(), checkpoint_name))
+
+        # Load the checkpoint.
+        try:
+            state_dict = torch.load(checkpoint_name, map_location='cpu')
+        except ModuleNotFoundError:
+            from megatron.fp16_deprecated import loss_scaler
+            # For backward compatibility.
+            print_rank_0(' > deserializing using the old code structure ...')
+            sys.modules['fp16.loss_scaler'] = sys.modules[
+                'megatron.fp16_deprecated.loss_scaler']
+            sys.modules['megatron.fp16.loss_scaler'] = sys.modules[
+                'megatron.fp16_deprecated.loss_scaler']
+            state_dict = torch.load(checkpoint_name, map_location='cpu')
+            sys.modules.pop('fp16.loss_scaler', None)
+            sys.modules.pop('megatron.fp16.loss_scaler', None)
+        except BaseException:
+            print_rank_0('could not load the BERT checkpoint')
+            sys.exit()
+
+        checkpoint_version = state_dict.get('checkpoint_version', 0)
+
+        # load the LM state dict into each model
+        model_dict = state_dict['model']['language_model']
+
+        if self.biencoder_shared_query_context_model:
+            self.model.language_model.load_state_dict(model_dict)
+            fix_query_key_value_ordering(self.model, checkpoint_version)
+        else:
+            if self.use_query_model:
+                self.query_model.language_model.load_state_dict(model_dict)
+                # give each model the same ict_head to begin with as well
+                if self.biencoder_projection_dim > 0:
+                    query_proj_state_dict = \
+                        self.state_dict_for_save_checkpoint()\
+                        [self._query_key]['projection_enc']
+                fix_query_key_value_ordering(self.query_model, checkpoint_version)
+
+            if self.use_context_model:
+                self.context_model.language_model.load_state_dict(model_dict)
+                if self.query_model is not None and \
+                    self.biencoder_projection_dim > 0:
+                    self.context_model.projection_enc.load_state_dict\
+                        (query_proj_state_dict)
+                fix_query_key_value_ordering(self.context_model, checkpoint_version)
+
+
+class PretrainedBertModel(MegatronModule):
+    """BERT-based encoder for queries or contexts used for
+    learned information retrieval."""
+
+    def __init__(self, num_tokentypes=2,
+            parallel_output=True):
+        super(PretrainedBertModel, self).__init__()
+
+        args = get_args()
+        tokenizer = get_tokenizer()
+        self.pad_id = tokenizer.pad
+        self.biencoder_projection_dim = args.biencoder_projection_dim
+        self.parallel_output = parallel_output
+        init_method = init_method_normal(args.init_method_std)
+        scaled_init_method = scaled_init_method_normal(
+            args.init_method_std, args.num_layers)
+
+        self.language_model, self._language_model_key = get_language_model(
+            num_tokentypes=num_tokentypes,
+            add_pooler=False,
+            encoder_attn_mask_type=AttnMaskType.padding,
+            init_method=init_method,
+            scaled_init_method=scaled_init_method)
+
+        if args.biencoder_projection_dim > 0:
+            self.projection_enc = get_linear_layer(args.hidden_size,
+                                                   args.biencoder_projection_dim,
+                                                   init_method)
+            self._projection_enc_key = 'projection_enc'
+
+    def forward(self, input_ids, attention_mask, tokentype_ids=None):
+        extended_attention_mask = attention_mask.unsqueeze(1)
+        #extended_attention_mask = bert_extended_attention_mask(attention_mask)
+        position_ids = bert_position_ids(input_ids)
+
+
+        lm_output = self.language_model(input_ids,
+                                        position_ids,
+                                        extended_attention_mask,
+                                        tokentype_ids=tokentype_ids)
+        # This mask will be used in average-pooling and max-pooling
+        pool_mask = (input_ids == self.pad_id).unsqueeze(2)
+
+        # Taking the representation of the [CLS] token of BERT
+        pooled_output = lm_output[:, 0, :]
+
+        # Converting to float16 dtype
+        pooled_output = pooled_output.to(lm_output.dtype)
+
+        # Output.
+        if self.biencoder_projection_dim:
+            pooled_output = self.projection_enc(pooled_output)
+
+        return pooled_output
+
+    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)
+
+        if self.biencoder_projection_dim > 0:
+            state_dict_[self._projection_enc_key] = \
+                self.projection_enc.state_dict(destination, prefix, keep_vars)
+
+        return state_dict_
+
+    def load_state_dict(self, state_dict, strict=True):
+        """Customized load."""
+        print_rank_0("loading BERT weights")
+        self.language_model.load_state_dict(
+            state_dict[self._language_model_key], strict=strict)
+
+        if self.biencoder_projection_dim > 0:
+            print_rank_0("loading projection head weights")
+            self.projection_enc.load_state_dict(
+                state_dict[self._projection_enc_key], strict=strict)

megatron/training.py

@@ -311,7 +311,7 @@ def setup_model_and_optimizer(model_provider_func):
     # We only support local DDP with multiple micro-batches.
     if get_num_microbatches() > 1:
         assert args.DDP_impl == 'local'
-    if len(model) == 1:
+    if len(model) > 1:
         assert args.DDP_impl == 'local'
     if mpu.get_pipeline_model_parallel_world_size() > 1:
         assert args.DDP_impl == 'local'
@@ -323,6 +323,8 @@ def setup_model_and_optimizer(model_provider_func):
                                            'init_state_dict_from_bert'):
             print("Initializing ICT from pretrained BERT model", flush=True)
             module.init_state_dict_from_bert()
+            if args.fp16:
+                optimizer.reload_model_params()
 
     return model, optimizer, lr_scheduler
 

pretrain_ict.py

@@ -14,6 +14,7 @@
 # limitations under the License.
 
 """Pretrain BERT for Inverse Cloze Task"""
+import math
 
 import torch
 import torch.distributed as dist
@@ -23,17 +24,21 @@ from megatron import get_args
 from megatron import print_rank_0
 from megatron import get_timers
 from megatron import mpu
+from megatron.data.biencoder_dataset_utils import get_ict_batch
 from megatron.data.dataset_utils import build_train_valid_test_datasets
+from megatron.model.biencoder_model import biencoder_model_provider
 from megatron.training import pretrain
 from megatron.utils import average_losses_across_data_parallel_group
-from megatron.model.realm_model import general_ict_model_provider
-from megatron.data.realm_dataset_utils import get_ict_batch
 
 
 def pretrain_ict_model_provider():
     args = get_args()
-    return general_ict_model_provider(False, False)
-
+    model = biencoder_model_provider(
+                only_context_model=False,
+                only_query_model=False,
+                biencoder_shared_query_context_model=\
+                    args.biencoder_shared_query_context_model)
+    return model
 
 def get_group_world_size_rank():
 
@@ -72,7 +77,6 @@ class AllgatherFromDataParallelRegion(torch.autograd.Function):
         output = output_list[rank].contiguous()
         return output
 
-
 def forward_step(data_iterator, model, input_tensor):
     """Forward step."""
     args = get_args()
@@ -80,37 +84,57 @@ def forward_step(data_iterator, model, input_tensor):
 
     # Get the batch.
     timers('batch-generator').start()
-    query_tokens, query_pad_mask, \
-    block_tokens, block_pad_mask, block_indices = get_ict_batch(data_iterator)
+    query_tokens, query_mask, \
+    context_tokens, context_mask, context_indices = get_ict_batch(data_iterator)
     timers('batch-generator').stop()
 
+    # Query and Context Types
+    query_types = torch.cuda.LongTensor(*query_tokens.shape).fill_(0)
+    context_types = torch.cuda.LongTensor(*context_tokens.shape).fill_(0)
 
     # Forward model.
-    query_logits, block_logits = model(query_tokens, query_pad_mask, block_tokens, block_pad_mask)
+    query_logits, context_logits = model(query_tokens, query_mask,
+                                    query_types, context_tokens,
+                                    context_mask, context_types)
+
     micro_batch_size = query_logits.shape[0]
-    global_batch_size = dist.get_world_size() * micro_batch_size  # recall we assert that tensor_model_parallel_size == 1
+    # recall we assert that tensor_model_parallel_size == 1
+    assert mpu.get_tensor_model_parallel_world_size() == 1, \
+        "Model parallel size > 1 not supported for ICT"
 
+    global_batch_size = dist.get_world_size() * micro_batch_size
     all_query_logits = AllgatherFromDataParallelRegion.apply(query_logits)
-    all_block_logits = AllgatherFromDataParallelRegion.apply(block_logits)
+    all_context_logits = AllgatherFromDataParallelRegion.apply(context_logits) 
+
+    # scores are inner products between query and context embeddings
+    retrieval_scores = torch.matmul(all_query_logits,
+                        torch.transpose(all_context_logits, 0, 1))
+    # scaling the retriever scores
+    if args.retriever_score_scaling:
+        retrieval_scores = retrieval_scores / math.sqrt(args.hidden_size)
 
-    # scores are inner products between query and block embeddings
-    retrieval_scores = all_query_logits.float().matmul(torch.transpose(all_block_logits, 0, 1).float())
-    softmaxed = F.softmax(retrieval_scores, dim=1)
-    sorted_vals, sorted_indices = torch.topk(softmaxed, k=softmaxed.shape[1], sorted=True)
+    softmax_scores = F.log_softmax(retrieval_scores, dim=1)
+    sorted_vals, sorted_indices = torch.topk(softmax_scores,
+                                    k=softmax_scores.shape[1], sorted=True)
 
     def topk_accuracy(k):
-        return torch.cuda.FloatTensor([sum([int(i in sorted_indices[i, :k]) for i in range(global_batch_size)]) / global_batch_size])
+        return torch.cuda.FloatTensor([sum([int(i in sorted_indices[i, :k]) \
+            for i in range(global_batch_size)]) / global_batch_size])
 
-    topk_accs = [topk_accuracy(int(k)) for k in args.report_topk_accuracies]
-    retrieval_loss = torch.nn.CrossEntropyLoss()(retrieval_scores, torch.arange(global_batch_size).long().cuda())
-    retrieval_loss = retrieval_loss.float()
-    averaged_losses = average_losses_across_data_parallel_group([retrieval_loss, *topk_accs])
+    topk_accs = [topk_accuracy(int(k)) for k in args.retriever_report_topk_accuracies]
 
-    # create stats_dict with retrieval loss and all specified top-k accuracies
-    topk_acc_dict = {'top{}_acc'.format(k): v for k, v in zip(args.report_topk_accuracies, averaged_losses[1:])}
-    stats_dict = dict(retrieval_loss=averaged_losses[0], **topk_acc_dict)
+    labels = torch.arange(global_batch_size).long().cuda()
+    loss = F.nll_loss(softmax_scores, labels, reduction='mean')
+    reduced_losses = average_losses_across_data_parallel_group([loss, *topk_accs])
+
+    # Scale the retrieval loss
+    loss = loss * mpu.get_data_parallel_world_size()
 
-    return retrieval_loss, stats_dict
+    # create stats_dict with retrieval loss and all specified top-k accuracies
+    topk_acc_dict = {'top{}_acc'.format(k): v * 100 for k, v in \
+                        zip(args.retriever_report_topk_accuracies, reduced_losses[1:])}
+    stats_dict = dict(loss=reduced_losses[0], **topk_acc_dict)
+    return loss, stats_dict
 
 
 def train_valid_test_datasets_provider(train_val_test_num_samples):
@@ -129,6 +153,7 @@ def train_valid_test_datasets_provider(train_val_test_num_samples):
         short_seq_prob=args.short_seq_prob,
         seed=args.seed,
         skip_warmup=(not args.mmap_warmup),
+        binary_head=False,
         dataset_type='ict')
     print_rank_0("> finished creating BERT ICT datasets ...")
 
@@ -136,5 +161,7 @@ def train_valid_test_datasets_provider(train_val_test_num_samples):
 
 
 if __name__ == "__main__":
-    pretrain(train_valid_test_datasets_provider, pretrain_ict_model_provider, forward_step,
+    pretrain(train_valid_test_datasets_provider,
+             pretrain_ict_model_provider,
+             forward_step,
              args_defaults={'tokenizer_type': 'BertWordPieceLowerCase'})