Enable check_reduction for imagenet flow and fairseq

Summary:
As the title says, better to enable this for certain use cases to make
sure things are right

Reviewed By: myleott, pietern

Differential Revision: D13351753

fbshipit-source-id: cf495960fda71ebd679c23212e19703c93a9dbdc

fairseq/models/distributed_fairseq_model.py

@@ -5,6 +5,7 @@
 # the root directory of this source tree. An additional grant of patent rights
 # can be found in the PATENTS file in the same directory.
 
+import inspect
 from torch.nn import parallel
 
 from fairseq.distributed_utils import c10d_status
@@ -46,6 +47,10 @@ def DistributedFairseqModel(args, model):
             broadcast_buffers=False,
             bucket_cap_mb=args.bucket_cap_mb,
         )
+        # Maintain backward compatibility for 0.4 or earlier
+        if 'check_reduction' in inspect.getargspec(ddp_class)[0]:
+            init_kwargs['check_reduction'] = True
+
     elif args.ddp_backend == 'no_c10d':
         ddp_class = LegacyDistributedDataParallel
         init_kwargs = dict(