DDP update

examples/run_squad.py

@@ -907,7 +907,7 @@ def main():
     #     except ImportError:
     #         raise ImportError("Please install apex from https://www.github.com/nvidia/apex to use distributed and fp16 training.")
 
-        model = torch.nn.parallel.DistributedDataParallel(model)
+        model = torch.nn.parallel.DistributedDataParallel(model, device_ids=[args.local_rank], output_device=args.local_rank)
     elif n_gpu > 1:
         model = torch.nn.DataParallel(model)