Add teardown hook to LightningDataModule

CHANGELOG.md

@@ -33,6 +33,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Added `LightningEnvironment` for Lightning-specific DDP ([#5915](https://github.com/PyTorchLightning/pytorch-lightning/pull/5915))
 
 
+- Added `teardown()` hook to LightningDataModule ([#4673](https://github.com/PyTorchLightning/pytorch-lightning/pull/4673))
+
+
 - Added `auto_insert_metric_name` parameter to `ModelCheckpoint` ([#6277](https://github.com/PyTorchLightning/pytorch-lightning/pull/6277))
 
 

docs/source/common/lightning_module.rst

@@ -1256,7 +1256,7 @@ prepare_data
 setup
 ~~~~~
 
-.. automethod:: pytorch_lightning.core.hooks.ModelHooks.setup
+.. automethod:: pytorch_lightning.core.hooks.DataHooks.setup
     :noindex:
 
 tbptt_split_batch
@@ -1268,7 +1268,7 @@ tbptt_split_batch
 teardown
 ~~~~~~~~
 
-.. automethod:: pytorch_lightning.core.hooks.ModelHooks.teardown
+.. automethod:: pytorch_lightning.core.hooks.DataHooks.teardown
     :noindex:
 
 train_dataloader

docs/source/extensions/datamodules.rst

@@ -94,6 +94,10 @@ The equivalent DataModule just organizes the same exact code, but makes it reusa
         def test_dataloader(self):
             return DataLoader(self.mnist_test, batch_size=self.batch_size)
 
+        def teardown(self, stage: Optional[str] = None):
+            # Used to clean-up when the run is finished
+            ...
+
 But now, as the complexity of your processing grows (transforms, multiple-GPU training), you can
 let Lightning handle those details for you while making this dataset reusable so you can share with
 colleagues or use in different projects.
@@ -243,7 +247,10 @@ There are also data operations you might want to perform on every GPU. Use setup
                 self.dims = getattr(self, 'dims', self.mnist_test[0][0].shape)
 
 
-.. warning:: `setup` is called from every process. Setting state here is okay.
+.. warning:: ``setup`` is called from every process. Setting state here is okay.
+
+
+.. note:: ``teardown`` can be used to clean up the state. It is also called from every process
 
 
 train_dataloader
@@ -411,10 +418,14 @@ You can of course use DataModules in plain PyTorch code as well.
     for batch in dm.val_dataloader():
         ...
 
+    dm.teardown(stage='fit')
+
     # lazy load test data
     dm.setup(stage='test')
     for batch in dm.test_dataloader():
         ...
 
+    dm.teardown(stage='test')
+
 But overall, DataModules encourage reproducibility by allowing all details of a dataset to be specified in a unified
 structure.

pytorch_lightning/core/datamodule.py

@@ -14,7 +14,6 @@
 """LightningDataModule for loading DataLoaders with ease."""
 
 import functools
-from abc import abstractmethod
 from argparse import ArgumentParser, Namespace
 from typing import Any, List, Mapping, Optional, Sequence, Tuple, Union
 
@@ -44,6 +43,8 @@ def __call__(cls, *args, **kwargs):
             cls.prepare_data = track_data_hook_calls(rank_zero_only(cls.prepare_data))
             # Track setup calls
             cls.setup = track_data_hook_calls(cls.setup)
+            # Track teardown calls
+            cls.teardown = track_data_hook_calls(cls.teardown)
 
         # Get instance of LightningDataModule by mocking its __init__ via __call__
         obj = type.__call__(cls, *args, **kwargs)
@@ -52,12 +53,13 @@ def __call__(cls, *args, **kwargs):
 
 
 def track_data_hook_calls(fn):
-    """A decorator that checks if prepare_data/setup have been called.
+    """A decorator that checks if prepare_data/setup/teardown has been called.
 
     - When ``dm.prepare_data()`` is called, ``dm.has_prepared_data`` gets set to True
     - When ``dm.setup()``, ``dm.has_setup_{fit,validate,test}`` get set to True
     - When ``dm.setup(stage)`` is called, where stage is any of ``{fit,validate,test,predict}``.
         Its corresponding `dm_has_setup_{stage}` attribute gets set to True
+    - ``dm.teardown()`` and ``dm.teardown(stage)`` act exactly like ``dm.setup``
 
     Args:
         fn (function): Function that will be tracked to see if it has been called.
@@ -71,9 +73,10 @@ def wrapped_fn(*args, **kwargs):
 
         # The object instance from which setup or prepare_data was called
         obj = args[0]
+        name = fn.__name__
 
         # If calling setup, we check the stage and assign stage-specific bool args
-        if fn.__name__ == "setup":
+        if name in ("setup", "teardown"):
 
             # Get stage either by grabbing from args or checking kwargs.
             # If not provided, set call status of 'fit', 'validate', and 'test' to True.
@@ -82,11 +85,11 @@ def wrapped_fn(*args, **kwargs):
 
             if stage is None:
                 for s in ("fit", "validate", "test"):
-                    setattr(obj, f"_has_setup_{s}", True)
+                    setattr(obj, f"_has_{name}_{s}", True)
             else:
-                setattr(obj, f"_has_setup_{stage}", True)
+                setattr(obj, f"_has_{name}_{stage}", True)
 
-        if fn.__name__ == "prepare_data":
+        elif name == "prepare_data":
             obj._has_prepared_data = True
 
         return fn(*args, **kwargs)
@@ -119,14 +122,18 @@ def val_dataloader(self):
             def test_dataloader(self):
                 test_split = Dataset(...)
                 return DataLoader(test_split)
+            def teardown(self):
+                # clean up after fit or test
+                # called on every process in DDP
 
-    A DataModule implements 5 key methods:
+    A DataModule implements 6 key methods:
 
     * **prepare_data** (things to do on 1 GPU/TPU not on every GPU/TPU in distributed mode).
     * **setup**  (things to do on every accelerator in distributed mode).
     * **train_dataloader** the training dataloader.
     * **val_dataloader** the val dataloader(s).
     * **test_dataloader** the test dataloader(s).
+    * **teardown** (things to do on every accelerator in distributed mode when finished)
 
 
     This allows you to share a full dataset without explaining how to download,
@@ -154,11 +161,17 @@ def __init__(
 
         # Private attrs to keep track of whether or not data hooks have been called yet
         self._has_prepared_data = False
+
         self._has_setup_fit = False
         self._has_setup_validate = False
         self._has_setup_test = False
         self._has_setup_predict = False
 
+        self._has_teardown_fit = False
+        self._has_teardown_validate = False
+        self._has_teardown_test = False
+        self._has_teardown_predict = False
+
     @property
     def train_transforms(self):
         """
@@ -259,13 +272,41 @@ def has_setup_predict(self) -> bool:
         """
         return self._has_setup_predict
 
-    @abstractmethod
-    def prepare_data(self, *args, **kwargs):
-        pass
+    @property
+    def has_teardown_fit(self) -> bool:
+        """Return bool letting you know if ``datamodule.teardown(stage='fit')`` has been called or not.
 
-    @abstractmethod
-    def setup(self, stage: Optional[str] = None):
-        pass
+        Returns:
+            bool: True ``if datamodule.teardown(stage='fit')`` has been called. False by default.
+        """
+        return self._has_teardown_fit
+
+    @property
+    def has_teardown_validate(self) -> bool:
+        """Return bool letting you know if ``datamodule.teardown(stage='validate')`` has been called or not.
+
+        Returns:
+            bool: True if ``datamodule.teardown(stage='validate')`` has been called. False by default.
+        """
+        return self._has_teardown_validate
+
+    @property
+    def has_teardown_test(self) -> bool:
+        """Return bool letting you know if ``datamodule.teardown(stage='test')`` has been called or not.
+
+        Returns:
+            bool: True if ``datamodule.teardown(stage='test')`` has been called. False by default.
+        """
+        return self._has_teardown_test
+
+    @property
+    def has_teardown_predict(self) -> bool:
+        """Return bool letting you know if ``datamodule.teardown(stage='predict')`` has been called or not.
+
+        Returns:
+            bool: True if ``datamodule.teardown(stage='predict')`` has been called. False by default.
+        """
+        return self._has_teardown_predict
 
     @classmethod
     def add_argparse_args(cls, parent_parser: ArgumentParser, **kwargs) -> ArgumentParser:

pytorch_lightning/core/hooks.py

@@ -25,42 +25,6 @@
 class ModelHooks:
     """Hooks to be used in LightningModule."""
 
-    def setup(self, stage: Optional[str] = None) -> None:
-        """
-        Called at the beginning of fit (train + validate), validate, test, predict, or tune.
-        This is a good hook when you need to build models dynamically or adjust something about them.
-        This hook is called on every process when using DDP.
-
-        Args:
-            stage: either ``'fit'``, ``'validate'``, ``'test'``, or ``'predict'``
-
-        Example::
-
-            class LitModel(...):
-                def __init__(self):
-                    self.l1 = None
-
-                def prepare_data(self):
-                    download_data()
-                    tokenize()
-
-                    # don't do this
-                    self.something = else
-
-                def setup(stage):
-                    data = Load_data(...)
-                    self.l1 = nn.Linear(28, data.num_classes)
-
-        """
-
-    def teardown(self, stage: Optional[str] = None) -> None:
-        """
-        Called at the end of fit (train + validate), validate, test, predict, or tune.
-
-        Args:
-            stage: either ``'fit'``, ``'validate'``, ``'test'``, or ``'predict'``
-        """
-
     def on_fit_start(self) -> None:
         """
         Called at the very beginning of fit.
@@ -383,6 +347,42 @@ def prepare_data(self):
             model.test_dataloader()
         """
 
+    def setup(self, stage: Optional[str] = None) -> None:
+        """
+        Called at the beginning of fit (train + validate), validate, test, predict, or tune.
+        This is a good hook when you need to build models dynamically or adjust something about them.
+        This hook is called on every process when using DDP.
+
+        Args:
+            stage: either ``'fit'``, ``'validate'``, ``'test'``, or ``'predict'``
+
+        Example::
+
+            class LitModel(...):
+                def __init__(self):
+                    self.l1 = None
+
+                def prepare_data(self):
+                    download_data()
+                    tokenize()
+
+                    # don't do this
+                    self.something = else
+
+                def setup(stage):
+                    data = Load_data(...)
+                    self.l1 = nn.Linear(28, data.num_classes)
+
+        """
+
+    def teardown(self, stage: Optional[str] = None) -> None:
+        """
+        Called at the end of fit (train + validate), validate, test, predict, or tune.
+
+        Args:
+            stage: either ``'fit'``, ``'validate'``, ``'test'``, or ``'predict'``
+        """
+
     def train_dataloader(self) -> Any:
         """
         Implement one or more PyTorch DataLoaders for training.

pytorch_lightning/trainer/trainer.py

@@ -1077,6 +1077,12 @@ def call_setup_hook(self, model: LightningModule) -> None:
 
     def call_teardown_hook(self, model: LightningModule) -> None:
         state = self._teardown_state
+
+        if self.datamodule is not None:
+            called = getattr(self.datamodule, f'has_teardown_{state}')
+            if not called:
+                self.datamodule.teardown(stage=state)
+
         self.profiler.teardown(stage=state)
         self.teardown(stage=state)
         model.teardown(stage=state)