[fbsync] Adding ViT to torchvision/models (#4594)

Summary:
* [vit] Adding ViT to torchvision/models

* adding pre-logits layer + resolving comments

* Fix the model attribute bug

* Change version to arch

* fix failing unittests

* remove useless prints

* reduce input size to fix unittests

* Increase windows-cpu executor to 2xlarge

* Use `batch_first=True` and remove classifier

* Change resource_class back to xlarge

* Remove vit_h_14

* Remove vit_h_14 from __all__

* Move vision_transformer.py into prototype

* Fix formatting issue

* remove arch in builder

* Fix type err in model builder

* address comments and trigger unittests

* remove the prototype import in torchvision.models

* Adding vit back to models to trigger CircleCI test

* fix test_jit_forward_backward

* Move all to prototype.

* Adopt new helper methods and fix prototype tests.

* Remove unused import.

Reviewed By: NicolasHug

Differential Revision: D32694316

fbshipit-source-id: fa2867555fb7ae65f8dab537517386f6694585a2

Co-authored-by: Vasilis Vryniotis <datumbox@users.noreply.github.com>
Co-authored-by: Vasilis Vryniotis <vvryniotis@fb.com>

test/test_backbone_utils.py

@@ -1,5 +1,6 @@
 import random
 from itertools import chain
+from typing import Mapping, Sequence
 
 import pytest
 import torch
@@ -89,7 +90,16 @@ def _create_feature_extractor(self, *args, **kwargs):
 
     def _get_return_nodes(self, model):
         set_rng_seed(0)
-        exclude_nodes_filter = ["getitem", "floordiv", "size", "chunk"]
+        exclude_nodes_filter = [
+            "getitem",
+            "floordiv",
+            "size",
+            "chunk",
+            "_assert",
+            "eq",
+            "dim",
+            "getattr",
+        ]
         train_nodes, eval_nodes = get_graph_node_names(
             model, tracer_kwargs={"leaf_modules": self.leaf_modules}, suppress_diff_warning=True
         )
@@ -144,7 +154,16 @@ def test_forward_backward(self, model_name):
             model, train_return_nodes=train_return_nodes, eval_return_nodes=eval_return_nodes
         )
         out = model(self.inp)
-        sum(o.mean() for o in out.values()).backward()
+        out_agg = 0
+        for node_out in out.values():
+            if isinstance(node_out, Sequence):
+                out_agg += sum(o.mean() for o in node_out if o is not None)
+            elif isinstance(node_out, Mapping):
+                out_agg += sum(o.mean() for o in node_out.values() if o is not None)
+            else:
+                # Assume that the only other alternative at this point is a Tensor
+                out_agg += node_out.mean()
+        out_agg.backward()
 
     def test_feature_extraction_methods_equivalence(self):
         model = models.resnet18(**self.model_defaults).eval()
@@ -176,7 +195,16 @@ def test_jit_forward_backward(self, model_name):
         )
         model = torch.jit.script(model)
         fgn_out = model(self.inp)
-        sum(o.mean() for o in fgn_out.values()).backward()
+        out_agg = 0
+        for node_out in fgn_out.values():
+            if isinstance(node_out, Sequence):
+                out_agg += sum(o.mean() for o in node_out if o is not None)
+            elif isinstance(node_out, Mapping):
+                out_agg += sum(o.mean() for o in node_out.values() if o is not None)
+            else:
+                # Assume that the only other alternative at this point is a Tensor
+                out_agg += node_out.mean()
+        out_agg.backward()
 
     def test_train_eval(self):
         class TestModel(torch.nn.Module):

test/test_models.py

@@ -507,6 +507,7 @@ def test_classification_model(model_fn, dev):
     }
     model_name = model_fn.__name__
     kwargs = {**defaults, **_model_params.get(model_name, {})}
+    num_classes = kwargs.get("num_classes")
     input_shape = kwargs.pop("input_shape")
 
     model = model_fn(**kwargs)
@@ -515,7 +516,7 @@ def test_classification_model(model_fn, dev):
     x = torch.rand(input_shape).to(device=dev)
     out = model(x)
     _assert_expected(out.cpu(), model_name, prec=0.1)
-    assert out.shape[-1] == 50
+    assert out.shape[-1] == num_classes
     _check_jit_scriptable(model, (x,), unwrapper=script_model_unwrapper.get(model_name, None))
     _check_fx_compatible(model, x)
 

test/test_prototype_models.py

@@ -122,8 +122,11 @@ def test_old_vs_new_factory(model_fn, module_name, dev):
         x = [x]
 
     # compare with new model builder parameterized in the old fashion way
-    model_old = _build_model(_get_original_model(model_fn), **kwargs).to(device=dev)
-    model_new = _build_model(model_fn, **kwargs).to(device=dev)
+    try:
+        model_old = _build_model(_get_original_model(model_fn), **kwargs).to(device=dev)
+        model_new = _build_model(model_fn, **kwargs).to(device=dev)
+    except ModuleNotFoundError:
+        pytest.skip(f"Model '{model_name}' not available in both modules.")
     torch.testing.assert_close(model_new(x), model_old(x), rtol=0.0, atol=0.0, check_dtype=False)
 
 

torchvision/prototype/models/__init__.py

@@ -10,6 +10,7 @@
 from .shufflenetv2 import *
 from .squeezenet import *
 from .vgg import *
+from .vision_transformer import *
 from . import detection
 from . import quantization
 from . import segmentation