quick patch __code__ (#1352)

* quick patch

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

* testing fix

pytorch_lightning/trainer/model_hooks.py

@@ -20,8 +20,17 @@ def is_overriden(self, method_name: str, model: LightningModule = None) -> bool:
             # in case of calling deprecated method
             return False
 
-        # when code pointers are different, it was overriden
-        is_overriden = getattr(model, method_name).__code__ is not getattr(super_object, method_name).__code__
+        instance_attr = getattr(model, method_name)
+        super_attr = getattr(super_object, method_name)
+
+        # when code pointers are different, it was implemented
+        if hasattr(instance_attr, 'patch_loader_code'):
+            # cannot pickle __code__ so cannot verify if PatchDataloader
+            # exists which shows dataloader methods have been overwritten.
+            # so, we hack it by using the string representation
+            is_overriden = instance_attr.patch_loader_code != str(super_attr.__code__)
+        else:
+            is_overriden = instance_attr.__code__ is not super_attr.__code__
         return is_overriden
 
     def has_arg(self, f_name, arg_name):

pytorch_lightning/trainer/trainer.py

@@ -970,8 +970,10 @@ class _PatchDataLoader(object):
     def __init__(self, dataloader: Union[List[DataLoader], DataLoader]):
         self.dataloader = dataloader
 
-        # Assign __code__, needed for checking if method has been overriden
-        self.__code__ = self.__call__.__code__
+        # cannot pickle __code__ so cannot verify if PatchDataloader
+        # exists which shows dataloader methods have been overwritten.
+        # so, we hack it by using the string representation
+        self.patch_loader_code = str(self.__call__.__code__)
 
     def __call__(self) -> Union[List[DataLoader], DataLoader]:
         return self.dataloader