Override broadcast_object_list for torch<1.8 (#7592)

Co-authored-by: Carlos Mocholi <[email protected]>

Author: awaelchli

CHANGELOG.md

@@ -10,7 +10,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 ### Fixed
 
 - Fixed `ProgressBar` pickling after calling `trainer.predict` ([#7608](https://github.com/PyTorchLightning/pytorch-lightning/pull/7608))
-
+- Fixed broadcasting in multi-node, multi-gpu DDP using torch 1.7 ([#7592](https://github.com/PyTorchLightning/pytorch-lightning/pull/7592))
 
 ## [1.3.2] - 2021-05-18
 

pytorch_lightning/overrides/torch_distributed.py

@@ -3,7 +3,7 @@
 
 import torch
 
-from pytorch_lightning.utilities.imports import _TORCH_GREATER_EQUAL_1_7
+from pytorch_lightning.utilities.imports import _TORCH_GREATER_EQUAL_1_8
 
 log = logging.getLogger(__name__)
 
@@ -88,7 +88,7 @@ def _broadcast_object_list(object_list, src=0, group=None):
             object_list[i] = _tensor_to_object(obj_view, obj_size)
 
 
-if _TORCH_GREATER_EQUAL_1_7 and torch.distributed.is_available():
+if _TORCH_GREATER_EQUAL_1_8 and torch.distributed.is_available():
     from torch.distributed.distributed_c10d import broadcast_object_list
 else:
     broadcast_object_list = _broadcast_object_list