ExperimentHparams class; Set state.train_dataloader (#966)

- Added in an `ExperimentHparams` class. This class describes how to run a training job that may have multiple calls to `Trainer.fit` and/or `Trainer.eval`. Specifically, `ExperimentHparams.initialize_object()` returns a `(Trainer, List[FitKwargs], List[EvalKwargs])` tuple, that then the user's entrypoint can consome.
  This class does not automatically train the model, nor does it include an entrypoint.
- Added typing definitions for `FitKwargs` and `EvalKwargs`, along with test cases to ensure they stay in sync with the Trainer signature.
- Fix an bug introduced in #948, which removed the setting of `State.train_dataloader`. Added back the lines to correctly set the train dataloader.

composer/callbacks/__init__.py

@@ -6,9 +6,9 @@
 Each callback inherits from the :class:`~composer.core.callback.Callback` base class. See detailed description and
 examples for writing your own callbacks at the :class:`~composer.core.callback.Callback` base class.
 """
-from composer.callbacks.callback_hparams import (CallbackHparams, CheckpointSaverHparams, GradMonitorHparams,
-                                                 LRMonitorHparams, MemoryMonitorHparams, MLPerfCallbackHparams,
-                                                 SpeedMonitorHparams)
+from composer.callbacks.callback_hparams import (CallbackHparams, CheckpointSaverHparams, EarlyStopperHparams,
+                                                 GradMonitorHparams, LRMonitorHparams, MemoryMonitorHparams,
+                                                 MLPerfCallbackHparams, SpeedMonitorHparams)
 from composer.callbacks.checkpoint_saver import CheckpointSaver
 from composer.callbacks.grad_monitor import GradMonitor
 from composer.callbacks.lr_monitor import LRMonitor
@@ -26,6 +26,7 @@
     # hparams objects
     "CallbackHparams",
     "CheckpointSaverHparams",
+    "EarlyStopperHparams",
     "GradMonitorHparams",
     "LRMonitorHparams",
     "MemoryMonitorHparams",

composer/trainer/__init__.py

@@ -5,8 +5,8 @@
 
 from composer.trainer import devices as devices
 from composer.trainer.trainer import Trainer
-from composer.trainer.trainer_hparams import TrainerHparams
+from composer.trainer.trainer_hparams import EvalHparams, ExperimentHparams, FitHparams, TrainerHparams
 
 load = TrainerHparams.load
 
-__all__ = ["Trainer", "TrainerHparams"]
+__all__ = ["Trainer", "TrainerHparams", "ExperimentHparams", "FitHparams", "EvalHparams"]

composer/trainer/trainer.py

@@ -804,6 +804,7 @@ def __init__(
         if self._train_data_spec is not None:
             self.state.set_dataloader(self._train_data_spec.dataloader, train_dataloader_label,
                                       train_subset_num_batches)
+            self.state.train_dataloader = self.state.dataloader
         self.train_metrics = _get_training_metrics(model) if compute_training_metrics else None
 
         # Max Duration
@@ -1106,6 +1107,7 @@ def fit(
         if train_dataloader is not None:
             self._train_data_spec = ensure_data_spec(train_dataloader)
             self.state.set_dataloader(self._train_data_spec.dataloader, train_dataloader_label)
+            self.state.train_dataloader = self.state.dataloader
         if self._train_data_spec is None:
             _raise_missing_argument_exception("train_dataloader")
         if train_subset_num_batches is not None: