Fix for multiple callbacks (Lightning-AI#6197)

* Fix for multiple callbacks

* Add CHANGELOG.md

* Remove old params

* Skip tests on windows using ddp

* Change name of the variable to not clash with should stop, which is separate

* Apply suggestions from code review

* Fix params

Co-authored-by: Jirka Borovec <Borda@users.noreply.github.com>

CHANGELOG.md

@@ -24,6 +24,9 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Fixed epoch level schedulers not being called when `val_check_interval < 1.0` ([#6075](https://github.com/PyTorchLightning/pytorch-lightning/pull/6075))
 
 
+- Fixed multiple early stopping callbacks ([#6197](https://github.com/PyTorchLightning/pytorch-lightning/pull/6197))
+
+
 ## [1.2.1] - 2021-02-23
 
 ### Fixed

pytorch_lightning/callbacks/early_stopping.py

@@ -181,15 +181,12 @@ def _run_early_stopping_check(self, trainer, pl_module):
         if self.monitor_op(current - self.min_delta, self.best_score):
             self.best_score = current
             self.wait_count = 0
-            should_stop = False
         else:
             self.wait_count += 1
-            should_stop = self.wait_count >= self.patience
 
-            if bool(should_stop):
+            if self.wait_count >= self.patience:
                 self.stopped_epoch = trainer.current_epoch
                 trainer.should_stop = True
 
         # stop every ddp process if any world process decides to stop
-        should_stop = trainer.training_type_plugin.reduce_early_stopping_decision(should_stop)
-        trainer.should_stop = should_stop
+        trainer.should_stop = trainer.training_type_plugin.reduce_early_stopping_decision(trainer.should_stop)

tests/callbacks/test_early_stopping.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 import os
 import pickle
+import sys
 from unittest import mock
 
 import cloudpickle
@@ -344,3 +345,57 @@ def validation_epoch_end(self, outputs):
 def test_early_stopping_mode_options():
     with pytest.raises(MisconfigurationException, match="`mode` can be auto, .* got unknown_option"):
         EarlyStopping(mode="unknown_option")
+
+
+class EarlyStoppingModel(BoringModel):
+
+    def __init__(self, expected_end_epoch):
+        super().__init__()
+        self.expected_end_epoch = expected_end_epoch
+
+    def validation_epoch_end(self, outputs):
+        losses = [8, 4, 2, 3, 4, 5, 8, 10]
+        val_loss = losses[self.current_epoch]
+        self.log('abc', torch.tensor(val_loss))
+        self.log('cba', torch.tensor(0))
+
+    def on_train_end(self) -> None:
+        assert self.trainer.current_epoch == self.expected_end_epoch, 'Early Stopping Failed'
+
+
+@pytest.mark.parametrize(
+    "callbacks, expected_stop_epoch, accelerator, num_processes",
+    [
+        ([EarlyStopping(monitor='abc'), EarlyStopping(monitor='cba', patience=3)], 3, None, 1),
+        ([EarlyStopping(monitor='cba', patience=3),
+          EarlyStopping(monitor='abc')], 3, None, 1),
+        pytest.param([EarlyStopping(monitor='abc'),
+                      EarlyStopping(monitor='cba', patience=3)],
+                     3,
+                     'ddp_cpu',
+                     2,
+                     marks=pytest.mark.skipif(sys.platform == "win32", reason="DDP not available on windows")),
+        pytest.param([EarlyStopping(monitor='cba', patience=3),
+                      EarlyStopping(monitor='abc')],
+                     3,
+                     'ddp_cpu',
+                     2,
+                     marks=pytest.mark.skipif(sys.platform == "win32", reason="DDP not available on windows")),
+    ],
+)
+def test_multiple_early_stopping_callbacks(callbacks, expected_stop_epoch, accelerator, num_processes, tmpdir):
+    """
+    Ensure when using multiple early stopping callbacks we stop if any signals we should stop.
+    """
+
+    model = EarlyStoppingModel(expected_stop_epoch)
+
+    trainer = Trainer(
+        default_root_dir=tmpdir,
+        callbacks=callbacks,
+        overfit_batches=0.20,
+        max_epochs=20,
+        accelerator=accelerator,
+        num_processes=num_processes
+    )
+    trainer.fit(model)