Un-balanced logging properly supported

pytorch_lightning/trainer/connectors/logger_connector/epoch_result_store.py

@@ -91,11 +91,13 @@ def check_dataloader_idx(self, result: Result) -> bool:
         random_key = list(result.keys())[-1]
         return result["meta"][random_key]["dataloader_idx"] is not None
 
-    def get_latest_from_func_name(self, latest_result, func_name: str, *args, **kwargs) -> Dict:
+    def get_latest_from_func_name(self, latest_result_opt, func_name: str, *args, **kwargs) -> Dict:
         results = {}
-        add_dataloader_idx = self.check_dataloader_idx(latest_result)
-        func = getattr(latest_result, func_name)
-        results.update(func(*args, add_dataloader_idx=add_dataloader_idx, **kwargs))
+        for opt_idx in latest_result_opt:
+            latest_result = latest_result_opt[opt_idx]
+            add_dataloader_idx = self.check_dataloader_idx(latest_result)
+            func = getattr(latest_result, func_name)
+            results.update(func(*args, add_dataloader_idx=add_dataloader_idx, **kwargs))
         return results
 
     def run_latest_batch_metrics_with_func_name(self, func_name, *args, **kwargs) -> List[Dict]:
@@ -156,6 +158,7 @@ def append(self, result, dataloader_idx: Optional[int] = None, extra_info: Optio
         assert isinstance(result, Result)
         if dataloader_idx is None:
             dataloader_idx = 0
+
         if extra_info is None:
             extra_info = {}
 
@@ -166,22 +169,27 @@ def append(self, result, dataloader_idx: Optional[int] = None, extra_info: Optio
             if dataloader_idx not in self._internals:
                 self._internals[dataloader_idx] = {}
                 self._internals_reduced[dataloader_idx] = defaultdict(dict)
+                self._latest_ref[dataloader_idx] = {}
 
             # extract infos
             opt_idx = extra_info["opt_idx"]
             batch_idx = extra_info["batch_idx"]
 
             self._append_to_structure(self._internals[dataloader_idx], opt_idx, batch_idx, result)
 
-            self._latest_ref[dataloader_idx] = result
+            self._latest_ref[dataloader_idx][opt_idx] = result
 
         # [dataloader_idx] is a list
         else:
             self._internal_type = ResultStoreType.OUTSIDE_BATCH_TRAIN_LOOP
             self._internals.setdefault(dataloader_idx, [])
             self._internals[dataloader_idx].append(result)
 
-            self._latest_ref[dataloader_idx] = result
+            if dataloader_idx not in self._latest_ref:
+                self._latest_ref[dataloader_idx] = {}
+                self._latest_ref[dataloader_idx][0] = {}
+
+            self._latest_ref[dataloader_idx][0] = result
 
     def auto_reduce_results_on_epoch_end(self) -> None:
         """
@@ -206,13 +214,9 @@ def auto_reduce_results_on_epoch_end(self) -> None:
                     # TODO: How to start training in middle of epoch
                     opt_outputs = epoch_metrics[opt_idx]
 
-                    num_batch_idx = len(self._internals[dl_idx][num_opt_idx]) - 1
-                    assert num_batch_idx >= 0
-                    batch_indexes = self._internals[dl_idx][num_opt_idx].keys()
-
                     # reduce across time first
                     time_reduced_outputs = []
-                    for batch_idx in batch_indexes:
+                    for batch_idx in opt_outputs.keys():
                         tbptt_outs = opt_outputs[batch_idx]
                         tbptt_outs = tbptt_outs[0].__class__.reduce_across_time(tbptt_outs)
                         if len(tbptt_outs) > 1:

tests/trainer/optimization/test_multiple_optimizers.py

@@ -0,0 +1,63 @@
+# Copyright The PyTorch Lightning team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# 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.
+"""
+Tests to ensure that the behaviours related to multiple optimizers works
+"""
+import torch
+
+import pytorch_lightning as pl
+from tests.base.boring_model import BoringModel
+
+
+def test_unbalanced_logging_with_multiple_optimizers(tmpdir):
+    """
+    This tests ensures reduction works in un-balanced logging settings
+    """
+    class TestModel(BoringModel):
+
+        loss_1 = []
+        loss_2 = []
+
+        def training_step(self, batch, batch_idx, optimizer_idx):
+            output = self.layer(batch)
+            loss = self.loss(batch, output)
+            if optimizer_idx == 0 and self.trainer.global_step > 10:
+                self.log("loss_1", loss, on_epoch=True, prog_bar=True)
+                self.loss_1.append(loss.detach().clone())
+            elif optimizer_idx == 1:
+                self.log("loss_2", loss, on_epoch=True, prog_bar=True)
+                self.loss_2.append(loss.detach().clone())
+            return {"loss": loss}
+
+        def configure_optimizers(self):
+            optimizer = torch.optim.SGD(self.layer.parameters(), lr=0.001)
+            optimizer2 = torch.optim.SGD(self.layer.parameters(), lr=0.001)
+            return [optimizer, optimizer2]
+
+    model = TestModel()
+    model.training_epoch_end = None
+
+    # Initialize a trainer
+    trainer = pl.Trainer(
+        default_root_dir=tmpdir,
+        max_epochs=1,
+    )
+
+    trainer.fit(model)
+
+    assert torch.equal(trainer.callback_metrics["loss_2_step"], model.loss_2[-1])
+    assert torch.equal(trainer.callback_metrics["loss_1_step"], model.loss_1[-1])
+    # test loss are properly reduced
+    assert torch.abs(trainer.callback_metrics["loss_2_epoch"] - torch.FloatTensor(model.loss_2).mean()) < 1e-6
+    assert torch.abs(trainer.callback_metrics["loss_1_epoch"] - torch.FloatTensor(model.loss_1).mean()) < 1e-6