added single node distdataparallel

pytorch_lightning/pt_overrides/override_data_parallel.py

@@ -28,6 +28,7 @@ class LightningDataParallel(DataParallel):
     """
 
     def parallel_apply(self, replicas, inputs, kwargs):
+        print('parallel_apply called')
         return parallel_apply(replicas, inputs, kwargs, self.device_ids[:len(replicas)])