Fixes #2455

Author: williamFalcon

pytorch_lightning/callbacks/early_stopping.py

@@ -152,7 +152,7 @@ def _run_early_stopping_check(self, trainer, pl_module):
             should_stop = torch.tensor(int(should_stop), device=pl_module.device)
             if trainer.use_ddp or trainer.use_ddp2:
                 dist.barrier()
-                dist.all_reduce(should_stop, op=dist.ReduceOp.MAX)
+                dist.all_reduce(should_stop, op=dist.reduce_op.MAX)
 
             print(f'RANK: {trainer.global_rank} SHOULD STOP: {should_stop} BEST: {self.best_score}')