Fix nn.DataParallel compatibility in PyTorch 1.5 (#4300)

* Test case for #3936

* multigpu tests pass on pytorch 1.4.0

* Fixup

* multigpu tests pass on pytorch 1.5.0

* Update src/transformers/modeling_utils.py

* Update src/transformers/modeling_utils.py

* rename multigpu to require_multigpu

* mode doc

src/transformers/modeling_albert.py

@@ -550,7 +550,7 @@ class AlbertModel(AlbertPreTrainedModel):
             token_type_ids = torch.zeros(input_shape, dtype=torch.long, device=device)
 
         extended_attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
-        extended_attention_mask = extended_attention_mask.to(dtype=next(self.parameters()).dtype)  # fp16 compatibility
+        extended_attention_mask = extended_attention_mask.to(dtype=self.dtype)  # fp16 compatibility
         extended_attention_mask = (1.0 - extended_attention_mask) * -10000.0
         head_mask = self.get_head_mask(head_mask, self.config.num_hidden_layers)
 

src/transformers/modeling_bert.py

@@ -703,9 +703,7 @@ class BertModel(BertPreTrainedModel):
 
         # We can provide a self-attention mask of dimensions [batch_size, from_seq_length, to_seq_length]
         # ourselves in which case we just need to make it broadcastable to all heads.
-        extended_attention_mask: torch.Tensor = self.get_extended_attention_mask(
-            attention_mask, input_shape, self.device
-        )
+        extended_attention_mask: torch.Tensor = self.get_extended_attention_mask(attention_mask, input_shape, device)
 
         # If a 2D ou 3D attention mask is provided for the cross-attention
         # we need to make broadcastabe to [batch_size, num_heads, seq_length, seq_length]

src/transformers/modeling_t5.py

@@ -704,7 +704,7 @@ class T5Stack(T5PreTrainedModel):
             past_key_value_states = [None] * len(self.block)
 
         # ourselves in which case we just need to make it broadcastable to all heads.
-        extended_attention_mask = self.get_extended_attention_mask(attention_mask, input_shape, self.device)
+        extended_attention_mask = self.get_extended_attention_mask(attention_mask, input_shape, inputs_embeds.device)
 
         if self.is_decoder and encoder_attention_mask is not None:
             encoder_extended_attention_mask = self.invert_attention_mask(encoder_attention_mask)

src/transformers/modeling_utils.py

@@ -17,7 +17,7 @@
 import inspect
 import logging
 import os
-from typing import Callable, Tuple
+from typing import Callable, List, Tuple
 
 import torch
 from torch import Tensor, device, dtype, nn
@@ -110,11 +110,33 @@ class ModuleUtilsMixin:
 
     @property
     def device(self) -> device:
+        try:
             return next(self.parameters()).device
+        except StopIteration:
+            # For nn.DataParallel compatibility in PyTorch 1.5
+
+            def find_tensor_attributes(module: nn.Module) -> List[Tuple[str, Tensor]]:
+                tuples = [(k, v) for k, v in module.__dict__.items() if torch.is_tensor(v)]
+                return tuples
+
+            gen = self._named_members(get_members_fn=find_tensor_attributes)
+            first_tuple = next(gen)
+            return first_tuple[1].device
 
     @property
     def dtype(self) -> dtype:
+        try:
             return next(self.parameters()).dtype
+        except StopIteration:
+            # For nn.DataParallel compatibility in PyTorch 1.5
+
+            def find_tensor_attributes(module: nn.Module) -> List[Tuple[str, Tensor]]:
+                tuples = [(k, v) for k, v in module.__dict__.items() if torch.is_tensor(v)]
+                return tuples
+
+            gen = self._named_members(get_members_fn=find_tensor_attributes)
+            first_tuple = next(gen)
+            return first_tuple[1].dtype
 
     def invert_attention_mask(self, encoder_attention_mask: Tensor) -> Tensor:
         """type: torch.Tensor -> torch.Tensor"""

src/transformers/modeling_xlnet.py

@@ -623,7 +623,7 @@ class XLNetModel(XLNetPreTrainedModel):
             mask_lo = torch.tril(attn_mask, diagonal=-1)
             ret = torch.cat([ret[:, :qlen] + mask_lo, ret[:, qlen:]], dim=1)
 
-        ret = ret.to(next(self.parameters()))
+        ret = ret.to(self.device)
         return ret
 
     def cache_mem(self, curr_out, prev_mem):
@@ -685,7 +685,7 @@ class XLNetModel(XLNetPreTrainedModel):
                 fwd_pos_seq = fwd_pos_seq.clamp(-self.clamp_len, self.clamp_len)
             pos_emb = self.positional_embedding(fwd_pos_seq, inv_freq, bsz)
 
-        pos_emb = pos_emb.to(next(self.parameters()))
+        pos_emb = pos_emb.to(self.device)
         return pos_emb
 
     @add_start_docstrings_to_callable(XLNET_INPUTS_DOCSTRING)
@@ -761,8 +761,8 @@ class XLNetModel(XLNetPreTrainedModel):
         mlen = mems[0].shape[0] if mems is not None and mems[0] is not None else 0
         klen = mlen + qlen
 
-        dtype_float = next(self.parameters()).dtype
-        device = next(self.parameters()).device
+        dtype_float = self.dtype
+        device = self.device
 
         # Attention mask
         # causal attention mask

tests/test_modeling_common.py

@@ -23,7 +23,7 @@ from typing import List
 
 from transformers import is_torch_available
 
-from .utils import require_torch, slow, torch_device
+from .utils import require_multigpu, require_torch, slow, torch_device
 
 
 if is_torch_available():
@@ -758,6 +758,31 @@ class ModelTesterMixin:
                         return True
         return False
 
+    @require_multigpu
+    def test_multigpu_data_parallel_forward(self):
+        config, inputs_dict = self.model_tester.prepare_config_and_inputs_for_common()
+
+        # some params shouldn't be scattered by nn.DataParallel
+        # so just remove them if they are present.
+        blacklist_non_batched_params = ["head_mask"]
+        for k in blacklist_non_batched_params:
+            inputs_dict.pop(k, None)
+
+        # move input tensors to cuda:O
+        for k, v in inputs_dict.items():
+            if torch.is_tensor(v):
+                inputs_dict[k] = v.to(0)
+
+        for model_class in self.all_model_classes:
+            model = model_class(config=config)
+            model.to(0)
+            model.eval()
+
+            # Wrap model in nn.DataParallel
+            model = torch.nn.DataParallel(model)
+            with torch.no_grad():
+                _ = model(**inputs_dict)
+
 
 global_rng = random.Random()
 

tests/test_modeling_ctrl.py

@@ -41,7 +41,7 @@ class CTRLModelTest(ModelTesterMixin, unittest.TestCase):
         def __init__(
             self,
             parent,
-            batch_size=13,
+            batch_size=14,
             seq_length=7,
             is_training=True,
             use_token_type_ids=True,

tests/test_modeling_gpt2.py

@@ -46,7 +46,7 @@ class GPT2ModelTest(ModelTesterMixin, unittest.TestCase):
         def __init__(
             self,
             parent,
-            batch_size=13,
+            batch_size=14,
             seq_length=7,
             is_training=True,
             use_token_type_ids=True,

tests/test_modeling_reformer.py

@@ -19,7 +19,7 @@ from transformers import is_torch_available
 
 from .test_configuration_common import ConfigTester
 from .test_modeling_common import ModelTesterMixin, floats_tensor, ids_tensor
-from .utils import require_torch, slow, torch_device
+from .utils import require_multigpu, require_torch, slow, torch_device
 
 
 if is_torch_available():
@@ -448,9 +448,14 @@ class ReformerTesterMixin:
         config_and_inputs = self.model_tester.prepare_config_and_inputs()
         self.model_tester.create_and_check_reformer_model_fp16_generate(*config_and_inputs)
 
+    @require_multigpu
+    def test_multigpu_data_parallel_forward(self):
+        # Opt-out of this test.
+        pass
+
 
 @require_torch
-class ReformerLocalAttnModelTest(ModelTesterMixin, ReformerTesterMixin, unittest.TestCase):
+class ReformerLocalAttnModelTest(ReformerTesterMixin, ModelTesterMixin, unittest.TestCase):
     all_model_classes = (ReformerModel, ReformerModelWithLMHead) if is_torch_available() else ()
     all_generative_model_classes = (ReformerModelWithLMHead,) if is_torch_available() else ()
     test_pruning = False
@@ -504,7 +509,7 @@ class ReformerLocalAttnModelTest(ModelTesterMixin, ReformerTesterMixin, unittest
 
 
 @require_torch
-class ReformerLSHAttnModelTest(ModelTesterMixin, unittest.TestCase, ReformerTesterMixin):
+class ReformerLSHAttnModelTest(ReformerTesterMixin, ModelTesterMixin, unittest.TestCase):
     all_model_classes = (ReformerModel, ReformerModelWithLMHead) if is_torch_available() else ()
     all_generative_model_classes = (ReformerModelWithLMHead,) if is_torch_available() else ()
     test_pruning = False

tests/test_modeling_transfo_xl.py

@@ -21,7 +21,7 @@ from transformers import is_torch_available
 
 from .test_configuration_common import ConfigTester
 from .test_modeling_common import ModelTesterMixin, ids_tensor
-from .utils import require_torch, slow, torch_device
+from .utils import require_multigpu, require_torch, slow, torch_device
 
 
 if is_torch_available():
@@ -43,7 +43,7 @@ class TransfoXLModelTest(ModelTesterMixin, unittest.TestCase):
         def __init__(
             self,
             parent,
-            batch_size=13,
+            batch_size=14,
             seq_length=7,
             mem_len=30,
             clamp_len=15,
@@ -207,6 +207,11 @@ class TransfoXLModelTest(ModelTesterMixin, unittest.TestCase):
         output_result = self.model_tester.create_transfo_xl_lm_head(*config_and_inputs)
         self.model_tester.check_transfo_xl_lm_head_output(output_result)
 
+    @require_multigpu
+    def test_multigpu_data_parallel_forward(self):
+        # Opt-out of this test.
+        pass
+
     @slow
     def test_model_from_pretrained(self):
         for model_name in list(TRANSFO_XL_PRETRAINED_MODEL_ARCHIVE_MAP.keys())[:1]:

tests/test_modeling_xlnet.py

@@ -61,7 +61,7 @@ class XLNetModelTest(ModelTesterMixin, unittest.TestCase):
         def __init__(
             self,
             parent,
-            batch_size=13,
+            batch_size=14,
             seq_length=7,
             mem_len=10,
             clamp_len=-1,

tests/utils.py

@@ -94,6 +94,25 @@ def require_tf(test_case):
     return test_case
 
 
+def require_multigpu(test_case):
+    """
+    Decorator marking a test that requires a multi-GPU setup (in PyTorch).
+
+    These tests are skipped on a machine without multiple GPUs.
+
+    To run *only* the multigpu tests, assuming all test names contain multigpu:
+    $ pytest -sv ./tests -k "multigpu"
+    """
+    if not _torch_available:
+        return unittest.skip("test requires PyTorch")(test_case)
+
+    import torch
+
+    if torch.cuda.device_count() < 2:
+        return unittest.skip("test requires multiple GPUs")(test_case)
+    return test_case
+
+
 if _torch_available:
     # Set the USE_CUDA environment variable to select a GPU.
     torch_device = "cuda" if parse_flag_from_env("USE_CUDA") else "cpu"