Loop Refactor 2/N - Remove Old Training Loop (#7985)

Co-authored-by: Justus Schock <justus.schock@rwth-aachen.de>
Co-authored-by: Justus Schock <justus.schock@posteo.de>
Co-authored-by: Justus Schock <12886177+justusschock@users.noreply.github.com>

CHANGELOG.md

@@ -125,6 +125,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
     * Simplified logic for updating the learning rate for schedulers ([#7682](https://github.com/PyTorchLightning/pytorch-lightning/pull/7682))
     * Removed the `on_epoch` guard from the "should stop" validation check ([#7701](https://github.com/PyTorchLightning/pytorch-lightning/pull/7701))
     * Refactored internal loop interface; added new classes `FitLoop`, `TrainingEpochLoop`, `TrainingBatchLoop` ([#7871](https://github.com/PyTorchLightning/pytorch-lightning/pull/7871))
+    * Removed `pytorch_lightning/trainer/training_loop.py` ([#7985](https://github.com/PyTorchLightning/pytorch-lightning/pull/7985))
 
 - Refactored logging
     * Renamed and moved `core/step_result.py` to `trainer/connectors/logger_connector/result.py` ([#7736](https://github.com/PyTorchLightning/pytorch-lightning/pull/7736))

pytorch_lightning/trainer/trainer.py

@@ -1229,10 +1229,10 @@ def _call_teardown_hook(self, model: LightningModule) -> None:
         model._current_dataloader_idx = None
 
     def call_hook(self, hook_name: str, *args, **kwargs) -> Any:
-        # Note this implementation is copy/pasted into the TrainLoop class in TrainLoop._on_train_epoch_end_hook
+        # Note this implementation is copy/pasted into the TrainLoop class in TrainingEpochLoop._on_train_epoch_end_hook
         # This was done to manage the deprecation of the `outputs` argument to on_train_epoch_end
         # If making changes to this function, ensure that those changes are also made to
-        # TrainLoop._on_train_epoch_end_hook
+        # TrainingEpochLoop._on_train_epoch_end_hook
         if self.lightning_module:
             prev_fx_name = self.lightning_module._current_fx_name
             self.lightning_module._current_fx_name = hook_name