Don't raise a warning when `nn.Module`s are not saved under hparams (#12669)

CHANGELOG.md

@@ -98,6 +98,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed `rank_zero_only` decorator in LSF environments ([#12587](https://github.com/PyTorchLightning/pytorch-lightning/pull/12587))
 
 
+- Don't raise a warning when `nn.Module` is not saved under hparams ([#12669](https://github.com/PyTorchLightning/pytorch-lightning/pull/12669))
+
+
 -
 
 

pytorch_lightning/utilities/parsing.py

@@ -234,17 +234,7 @@ def save_hyperparameters(
         ignore = [arg for arg in ignore if isinstance(arg, str)]
 
     ignore = list(set(ignore))
-
-    for k in list(init_args):
-        if k in ignore:
-            del init_args[k]
-            continue
-
-        if isinstance(init_args[k], nn.Module):
-            rank_zero_warn(
-                f"Attribute {k!r} is an instance of `nn.Module` and is already saved during checkpointing."
-                f" It is recommended to ignore them using `self.save_hyperparameters(ignore=[{k!r}])`."
-            )
+    init_args = {k: v for k, v in init_args.items() if k not in ignore}
 
     if not args:
         # take all arguments
@@ -266,6 +256,13 @@ def save_hyperparameters(
     # make deep copy so there is not other runtime changes reflected
     obj._hparams_initial = copy.deepcopy(obj._hparams)
 
+    for k, v in obj._hparams.items():
+        if isinstance(v, nn.Module):
+            rank_zero_warn(
+                f"Attribute {k!r} is an instance of `nn.Module` and is already saved during checkpointing."
+                f" It is recommended to ignore them using `self.save_hyperparameters(ignore=[{k!r}])`."
+            )
+
 
 class AttributeDict(Dict):
     """Extended dictionary accessible with dot notation.

tests/models/test_hparams.py

@@ -34,6 +34,7 @@ from pytorch_lightning.utilities import _HYDRA_EXPERIMENTAL_AVAILABLE, _OMEGACON
 from pytorch_lightning.utilities.exceptions import MisconfigurationException
 from tests.helpers import BoringModel, RandomDataset
 from tests.helpers.runif import RunIf
+from tests.helpers.utils import no_warning_call
 
 if _HYDRA_EXPERIMENTAL_AVAILABLE:
     from hydra.experimental import compose, initialize
@@ -819,18 +820,28 @@ def test_colliding_hparams(tmpdir):
         trainer.fit(model, datamodule=data)
 
 
-def test_nn_modules_raises_warning_when_saved_as_hparams():
+def test_nn_modules_warning_when_saved_as_hparams():
     class TorchModule(torch.nn.Module):
         def __init__(self):
             super().__init__()
             self.l1 = torch.nn.Linear(4, 5)
 
-    class CustomBoringModel(BoringModel):
+    class CustomBoringModelWarn(BoringModel):
         def __init__(self, encoder, decoder, other_hparam=7):
             super().__init__()
             self.save_hyperparameters()
 
     with pytest.warns(UserWarning, match="is an instance of `nn.Module` and is already saved"):
-        model = CustomBoringModel(encoder=TorchModule(), decoder=TorchModule())
+        model = CustomBoringModelWarn(encoder=TorchModule(), decoder=TorchModule())
 
     assert list(model.hparams) == ["encoder", "decoder", "other_hparam"]
+
+    class CustomBoringModelNoWarn(BoringModel):
+        def __init__(self, encoder, decoder, other_hparam=7):
+            super().__init__()
+            self.save_hyperparameters("other_hparam")
+
+    with no_warning_call(UserWarning, match="is an instance of `nn.Module` and is already saved"):
+        model = CustomBoringModelNoWarn(encoder=TorchModule(), decoder=TorchModule())
+
+    assert list(model.hparams) == ["other_hparam"]