Revert "add 'find_unused_parameters' in dist train"

This reverts commit 10830bc7.

mmdet/apis/train.py

@@ -206,14 +206,9 @@ def _dist_train(model,
     ]
     # put model on gpus
     # model = MMDistributedDataParallel(model.cuda())
-    find_unused_parameters = True
-    # Sets the `find_unused_parameters` parameter in
-    # torch.nn.parallel.DistributedDataParallel
-    model = MMDistributedDataParallel(
-        model.cuda(),
-        device_ids=[torch.cuda.current_device()],
-        broadcast_buffers=False,
-        find_unused_parameters=find_unused_parameters)
+    model = MMDistributedDataParallel(model.cuda(), 
+                                      device_ids=[torch.cuda.current_device()], 
+                                      broadcast_buffers=False)
 
     # build runner
     optimizer = build_optimizer(model, cfg.optimizer)

tools/test.py

@@ -240,11 +240,7 @@ def main():
         model = MMDataParallel(model, device_ids=[0])
         outputs = single_gpu_test(model, data_loader, args.show)
     else:
-        # model = MMDistributedDataParallel(model.cuda())
-        model = MMDistributedDataParallel(
-            model.cuda(),
-            device_ids=[torch.cuda.current_device()],
-            broadcast_buffers=False)
+        model = MMDistributedDataParallel(model.cuda())
         outputs = multi_gpu_test(model, data_loader, args.tmpdir,
                                  args.gpu_collect)
 

tools/test_robustness.py

@@ -375,11 +375,7 @@ def main():
                 model = MMDataParallel(model, device_ids=[0])
                 outputs = single_gpu_test(model, data_loader, args.show)
             else:
-                # model = MMDistributedDataParallel(model.cuda())
-                model = MMDistributedDataParallel(
-                    model.cuda(),
-                    device_ids=[torch.cuda.current_device()],
-                    broadcast_buffers=False)
+                model = MMDistributedDataParallel(model.cuda())
                 outputs = multi_gpu_test(model, data_loader, args.tmpdir)
 
             rank, _ = get_dist_info()