set dp as default backend

pytorch_lightning/pt_overrides/override_data_parallel.py

@@ -43,6 +43,7 @@ class LightningDataParallel(DataParallel):
     """
 
     def parallel_apply(self, replicas, inputs, kwargs):
+        print('LDP')
         return parallel_apply(replicas, inputs, kwargs, self.device_ids[:len(replicas)])
 
 
@@ -55,6 +56,7 @@ class LightningDistributedDataParallel(DistributedDataParallel):
         return parallel_apply(replicas, inputs, kwargs, self.device_ids[:len(replicas)])
 
     def forward(self, *inputs, **kwargs):
+        print('LDDP')
         self._sync_params()
         if self.device_ids:
             inputs, kwargs = self.scatter(inputs, kwargs, self.device_ids)