Log when we are using gradient accumulation (#647)

Summary: Pull Request resolved: #647

Reviewed By: vreis

Differential Revision: D24840948 (3c012ba)

fbshipit-source-id: 6e6837cd5b742ae185a9ae7959031865d7d237e3

classy_vision/tasks/classification_task.py

@@ -717,7 +717,7 @@ def prepare(self):
         if self.simulated_global_batchsize is not None:
             if self.simulated_global_batchsize % self.get_global_batchsize() != 0:
                 raise ValueError(
-                    f"Global batch size ({self.get_global_batchsize()}) must divide"
+                    f"Global batch size ({self.get_global_batchsize()}) must divide "
                     f"simulated_global_batchsize ({self.simulated_global_batchsize})"
                 )
         else:
@@ -726,6 +726,10 @@ def prepare(self):
         self.optimizer_period = (
             self.simulated_global_batchsize // self.get_global_batchsize()
         )
+        if self.optimizer_period > 1:
+            logging.info(
+                f"Using gradient accumulation with a period of {self.optimizer_period}"
+            )
 
         if self.checkpoint_path:
             self.checkpoint_dict = load_and_broadcast_checkpoint(self.checkpoint_path)