Replace .get_model() with explicit .lightning_module (#6035)

* rename get_model -> lightning_module

* update references to get_model

* pep8

* add proper deprecation

* remove outdated _get_reference_model

* fix cyclic import

Author: awaelchli

CHANGELOG.md

@@ -237,6 +237,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Deprecated using `'val_loss'` to set the `ModelCheckpoint` monitor ([#6012](https://github.com/PyTorchLightning/pytorch-lightning/pull/6012))
 
 
+- Deprecated `.get_model()` with explicit `.lightning_module` property ([#6035](https://github.com/PyTorchLightning/pytorch-lightning/pull/6035))
+
+
 ### Removed
 
 - Removed deprecated checkpoint argument `filepath` ([#5321](https://github.com/PyTorchLightning/pytorch-lightning/pull/5321))

pytorch_lightning/core/optimizer.py

@@ -101,11 +101,11 @@ def _to_lightning_optimizer(cls, optimizer, trainer, opt_idx):
         return optimizer
 
     def _toggle_model(self):
-        model_ref = self._trainer.get_model()
+        model_ref = self._trainer.lightning_module
         model_ref.toggle_optimizer(self, self._optimizer_idx)
 
     def _untoggle_model(self):
-        model_ref = self._trainer.get_model()
+        model_ref = self._trainer.lightning_module
         model_ref.untoggle_optimizer(self)
 
     @contextmanager
@@ -129,7 +129,7 @@ def toggle_model(self, sync_grad: bool = True):
     def __optimizer_step(self, closure: Optional[Callable] = None, profiler_name: str = None, **kwargs):
         trainer = self._trainer
         optimizer = self._optimizer
-        model = trainer.get_model()
+        model = trainer.lightning_module
 
         with trainer.profiler.profile(profiler_name):
             trainer.accelerator_backend.optimizer_step(optimizer, self._optimizer_idx, lambda_closure=closure, **kwargs)

pytorch_lightning/trainer/callback_hook.py

@@ -14,17 +14,18 @@
 
 from abc import ABC
 from copy import deepcopy
-from typing import Callable, List
+from typing import List
 
 from pytorch_lightning.callbacks import Callback
+from pytorch_lightning.core.lightning import LightningModule
 
 
 class TrainerCallbackHookMixin(ABC):
 
     # this is just a summary on variables used in this abstract class,
     # the proper values/initialisation should be done in child class
     callbacks: List[Callback] = []
-    get_model: Callable
+    lightning_module: LightningModule
 
     def on_before_accelerator_backend_setup(self, model):
         """Called in the beginning of fit and test"""
@@ -39,7 +40,7 @@ def setup(self, model, stage: str):
     def teardown(self, stage: str):
         """Called at the end of fit and test"""
         for callback in self.callbacks:
-            callback.teardown(self, self.get_model(), stage)
+            callback.teardown(self, self.lightning_module, stage)
 
     def on_init_start(self):
         """Called when the trainer initialization begins, model has not yet been set."""
@@ -54,72 +55,72 @@ def on_init_end(self):
     def on_fit_start(self):
         """Called when the trainer initialization begins, model has not yet been set."""
         for callback in self.callbacks:
-            callback.on_fit_start(self, self.get_model())
+            callback.on_fit_start(self, self.lightning_module)
 
     def on_fit_end(self):
         """Called when the trainer initialization begins, model has not yet been set."""
         for callback in self.callbacks:
-            callback.on_fit_end(self, self.get_model())
+            callback.on_fit_end(self, self.lightning_module)
 
     def on_sanity_check_start(self):
         """Called when the validation sanity check starts."""
         for callback in self.callbacks:
-            callback.on_sanity_check_start(self, self.get_model())
+            callback.on_sanity_check_start(self, self.lightning_module)
 
     def on_sanity_check_end(self):
         """Called when the validation sanity check ends."""
         for callback in self.callbacks:
-            callback.on_sanity_check_end(self, self.get_model())
+            callback.on_sanity_check_end(self, self.lightning_module)
 
     def on_train_epoch_start(self):
         """Called when the epoch begins."""
         for callback in self.callbacks:
-            callback.on_train_epoch_start(self, self.get_model())
+            callback.on_train_epoch_start(self, self.lightning_module)
 
     def on_train_epoch_end(self, outputs):
         """Called when the epoch ends."""
         for callback in self.callbacks:
-            callback.on_train_epoch_end(self, self.get_model(), outputs)
+            callback.on_train_epoch_end(self, self.lightning_module, outputs)
 
     def on_validation_epoch_start(self):
         """Called when the epoch begins."""
         for callback in self.callbacks:
-            callback.on_validation_epoch_start(self, self.get_model())
+            callback.on_validation_epoch_start(self, self.lightning_module)
 
     def on_validation_epoch_end(self):
         """Called when the epoch ends."""
         for callback in self.callbacks:
-            callback.on_validation_epoch_end(self, self.get_model())
+            callback.on_validation_epoch_end(self, self.lightning_module)
 
     def on_test_epoch_start(self):
         """Called when the epoch begins."""
         for callback in self.callbacks:
-            callback.on_test_epoch_start(self, self.get_model())
+            callback.on_test_epoch_start(self, self.lightning_module)
 
     def on_test_epoch_end(self):
         """Called when the epoch ends."""
         for callback in self.callbacks:
-            callback.on_test_epoch_end(self, self.get_model())
+            callback.on_test_epoch_end(self, self.lightning_module)
 
     def on_epoch_start(self):
         """Called when the epoch begins."""
         for callback in self.callbacks:
-            callback.on_epoch_start(self, self.get_model())
+            callback.on_epoch_start(self, self.lightning_module)
 
     def on_epoch_end(self):
         """Called when the epoch ends."""
         for callback in self.callbacks:
-            callback.on_epoch_end(self, self.get_model())
+            callback.on_epoch_end(self, self.lightning_module)
 
     def on_train_start(self):
         """Called when the train begins."""
         for callback in self.callbacks:
-            callback.on_train_start(self, self.get_model())
+            callback.on_train_start(self, self.lightning_module)
 
     def on_train_end(self):
         """Called when the train ends."""
         for callback in self.callbacks:
-            callback.on_train_end(self, self.get_model())
+            callback.on_train_end(self, self.lightning_module)
 
     def on_pretrain_routine_start(self, model):
         """Called when the train begins."""
@@ -134,74 +135,74 @@ def on_pretrain_routine_end(self, model):
     def on_batch_start(self):
         """Called when the training batch begins."""
         for callback in self.callbacks:
-            callback.on_batch_start(self, self.get_model())
+            callback.on_batch_start(self, self.lightning_module)
 
     def on_batch_end(self):
         """Called when the training batch ends."""
         for callback in self.callbacks:
-            callback.on_batch_end(self, self.get_model())
+            callback.on_batch_end(self, self.lightning_module)
 
     def on_train_batch_start(self, batch, batch_idx, dataloader_idx):
         """Called when the training batch begins."""
         for callback in self.callbacks:
-            callback.on_train_batch_start(self, self.get_model(), batch, batch_idx, dataloader_idx)
+            callback.on_train_batch_start(self, self.lightning_module, batch, batch_idx, dataloader_idx)
 
     def on_train_batch_end(self, outputs, batch, batch_idx, dataloader_idx):
         """Called when the training batch ends."""
         for callback in self.callbacks:
-            callback.on_train_batch_end(self, self.get_model(), outputs, batch, batch_idx, dataloader_idx)
+            callback.on_train_batch_end(self, self.lightning_module, outputs, batch, batch_idx, dataloader_idx)
 
     def on_validation_batch_start(self, batch, batch_idx, dataloader_idx):
         """Called when the validation batch begins."""
         for callback in self.callbacks:
-            callback.on_validation_batch_start(self, self.get_model(), batch, batch_idx, dataloader_idx)
+            callback.on_validation_batch_start(self, self.lightning_module, batch, batch_idx, dataloader_idx)
 
     def on_validation_batch_end(self, outputs, batch, batch_idx, dataloader_idx):
         """Called when the validation batch ends."""
         for callback in self.callbacks:
-            callback.on_validation_batch_end(self, self.get_model(), outputs, batch, batch_idx, dataloader_idx)
+            callback.on_validation_batch_end(self, self.lightning_module, outputs, batch, batch_idx, dataloader_idx)
 
     def on_test_batch_start(self, batch, batch_idx, dataloader_idx):
         """Called when the test batch begins."""
         for callback in self.callbacks:
-            callback.on_test_batch_start(self, self.get_model(), batch, batch_idx, dataloader_idx)
+            callback.on_test_batch_start(self, self.lightning_module, batch, batch_idx, dataloader_idx)
 
     def on_test_batch_end(self, outputs, batch, batch_idx, dataloader_idx):
         """Called when the test batch ends."""
         for callback in self.callbacks:
-            callback.on_test_batch_end(self, self.get_model(), outputs, batch, batch_idx, dataloader_idx)
+            callback.on_test_batch_end(self, self.lightning_module, outputs, batch, batch_idx, dataloader_idx)
 
     def on_validation_start(self):
         """Called when the validation loop begins."""
         for callback in self.callbacks:
-            callback.on_validation_start(self, self.get_model())
+            callback.on_validation_start(self, self.lightning_module)
 
     def on_validation_end(self):
         """Called when the validation loop ends."""
         for callback in self.callbacks:
-            callback.on_validation_end(self, self.get_model())
+            callback.on_validation_end(self, self.lightning_module)
 
     def on_test_start(self):
         """Called when the test begins."""
         for callback in self.callbacks:
-            callback.on_test_start(self, self.get_model())
+            callback.on_test_start(self, self.lightning_module)
 
     def on_test_end(self):
         """Called when the test ends."""
         for callback in self.callbacks:
-            callback.on_test_end(self, self.get_model())
+            callback.on_test_end(self, self.lightning_module)
 
     def on_keyboard_interrupt(self):
         """Called when the training is interrupted by KeyboardInterrupt."""
         for callback in self.callbacks:
-            callback.on_keyboard_interrupt(self, self.get_model())
+            callback.on_keyboard_interrupt(self, self.lightning_module)
 
     def on_save_checkpoint(self):
         """Called when saving a model checkpoint."""
         callback_states = {}
         for callback in self.callbacks:
             callback_class = type(callback)
-            state = callback.on_save_checkpoint(self, self.get_model())
+            state = callback.on_save_checkpoint(self, self.lightning_module)
             if state:
                 callback_states[callback_class] = state
         return callback_states
@@ -224,11 +225,11 @@ def on_after_backward(self):
         Called after loss.backward() and before optimizers do anything.
         """
         for callback in self.callbacks:
-            callback.on_after_backward(self, self.get_model())
+            callback.on_after_backward(self, self.lightning_module)
 
     def on_before_zero_grad(self, optimizer):
         """
         Called after optimizer.step() and before optimizer.zero_grad().
         """
         for callback in self.callbacks:
-            callback.on_before_zero_grad(self, self.get_model(), optimizer)
+            callback.on_before_zero_grad(self, self.lightning_module, optimizer)

pytorch_lightning/trainer/connectors/checkpoint_connector.py

@@ -94,7 +94,7 @@ def restore(self, checkpoint_path: str, on_gpu: bool) -> bool:
         checkpoint = pl_load(checkpoint_path, map_location=lambda storage, loc: storage)
 
         # acquire the model
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
 
         # restore model and datamodule state
         self.restore_model_state(model, checkpoint)
@@ -214,7 +214,7 @@ def hpc_save(self, folderpath: str, logger):
         filepath = os.path.join(folderpath, f'hpc_ckpt_{ckpt_number}.ckpt')
 
         # give model a chance to do something on hpc_save
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
         checkpoint = self.dump_checkpoint()
 
         model.on_hpc_save(checkpoint)
@@ -307,7 +307,7 @@ def dump_checkpoint(self, weights_only: bool = False) -> dict:
                 checkpoint['amp_scaling_state'] = amp.state_dict()
 
         # add the hyper_parameters and state_dict from the model
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
 
         # dump the module_arguments and state_dict from the model
         checkpoint['state_dict'] = model.state_dict()
@@ -339,7 +339,7 @@ def hpc_load(self, checkpoint_path: str, on_gpu: bool):
         checkpoint = pl_load(checkpoint_path, map_location=lambda storage, loc: storage)
 
         # acquire the model
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
 
         # restore model and datamodule state
         self.restore_model_state(model, checkpoint)

pytorch_lightning/trainer/connectors/logger_connector/epoch_result_store.py

@@ -235,7 +235,7 @@ def info(self):
         """
         This function provides necessary parameters to properly configure HookResultStore obj
         """
-        model_ref = self.trainer.get_model()
+        model_ref = self.trainer.lightning_module
         return {
             "batch_idx": self.trainer.batch_idx,
             "fx_name": model_ref._current_hook_fx_name or model_ref._current_fx_name,
@@ -252,7 +252,7 @@ def reset_model(self):
         """
         This function is used to reset model state at the end of the capture
         """
-        model_ref = self.trainer.get_model()
+        model_ref = self.trainer.lightning_module
         model_ref._results = Result()
         model_ref._current_hook_fx_name = None
         model_ref._current_fx_name = ''
@@ -263,7 +263,7 @@ def cache_result(self) -> None:
         and store the result object
         """
         with self.trainer.profiler.profile("cache_result"):
-            model_ref = self.trainer.get_model()
+            model_ref = self.trainer.lightning_module
 
             # extract hook results
             hook_result = model_ref._results

pytorch_lightning/trainer/connectors/logger_connector/logger_connector.py

@@ -82,7 +82,7 @@ def cached_results(self) -> Union[EpochResultStore, None]:
 
     def get_metrics(self, key: str) -> Dict:
         metrics_holder = getattr(self, f"_{key}", None)
-        model_ref = self.trainer.get_model()
+        model_ref = self.trainer.lightning_module
         metrics_holder.convert(
             self.trainer._device_type == DeviceType.TPU,
             model_ref.device if model_ref is not None else model_ref,
@@ -103,7 +103,7 @@ def check_logging_in_callbacks(self, hook_fx_name, on_step: bool = None, on_epoc
 
     def on_evaluation_batch_start(self, testing, batch, dataloader_idx, num_dataloaders):
         # Todo: required argument `testing` is not used
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
         # set dataloader_idx only if multiple ones
         model._current_dataloader_idx = dataloader_idx if num_dataloaders > 1 else None
         # track batch_size
@@ -263,7 +263,7 @@ def track_metrics_deprecated(self, deprecated_eval_results):
     def evaluation_epoch_end(self, testing):
         # Todo: required argument `testing` is not used
         # reset dataloader idx
-        model_ref = self.trainer.get_model()
+        model_ref = self.trainer.lightning_module
         model_ref._current_dataloader_idx = None
 
         # setting `has_batch_loop_finished` to True
@@ -408,7 +408,7 @@ def log_train_epoch_end_metrics(
         # epoch_output[optimizer_idx][training_step_idx][tbptt_index]
         # remember that not using truncated backprop is equivalent with truncated back prop of len(1)
 
-        model = self.trainer.get_model()
+        model = self.trainer.lightning_module
 
         epoch_callback_metrics = {}
 

pytorch_lightning/trainer/connectors/model_connector.py

@@ -25,7 +25,7 @@ def __init__(self, trainer):
         self.trainer = trainer
 
     def copy_trainer_model_properties(self, model):
-        ref_model = self._get_reference_model(model)
+        ref_model = self.trainer.lightning_module or model
 
         automatic_optimization = ref_model.automatic_optimization and self.trainer.train_loop.automatic_optimization
         self.trainer.train_loop.automatic_optimization = automatic_optimization
@@ -37,11 +37,3 @@ def copy_trainer_model_properties(self, model):
             m.use_amp = self.trainer.amp_backend is not None
             m.testing = self.trainer.testing
             m.precision = self.trainer.precision
-
-    def get_model(self):
-        return self._get_reference_model(self.trainer.model)
-
-    def _get_reference_model(self, model):
-        if self.trainer.accelerator_backend and self.trainer.accelerator_backend.lightning_module:
-            return self.trainer.accelerator_backend.lightning_module
-        return model

pytorch_lightning/trainer/deprecated_api.py

@@ -11,6 +11,7 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
+from pytorch_lightning.core.lightning import LightningModule
 from pytorch_lightning.trainer.connectors.accelerator_connector import AcceleratorConnector
 from pytorch_lightning.trainer.states import RunningStage
 from pytorch_lightning.utilities import DeviceType, DistributedType, rank_zero_warn
@@ -130,3 +131,15 @@ def use_single_gpu(self, val: bool) -> None:
         )
         if val:
             self.accelerator_connector._device_type = DeviceType.GPU
+
+
+class DeprecatedModelAttributes:
+
+    lightning_module = LightningModule
+
+    def get_model(self) -> LightningModule:
+        rank_zero_warn(
+            "The use of `Trainer.get_model()` is deprecated in favor of `Trainer.lightning_module`"
+            " and will be removed in v1.4.", DeprecationWarning
+        )
+        return self.lightning_module