!2886 only save ckpt in rank0 for Transformer

Merge pull request !2886 from yuchaojie/transformer

model_zoo/Transformer/train.py

@@ -147,10 +147,11 @@ def run_transformer_train():
 
     callbacks = [TimeMonitor(dataset.get_dataset_size()), LossCallBack()]
     if args.enable_save_ckpt == "true":
-        ckpt_config = CheckpointConfig(save_checkpoint_steps=args.save_checkpoint_steps,
-                                       keep_checkpoint_max=args.save_checkpoint_num)
-        ckpoint_cb = ModelCheckpoint(prefix='transformer', directory=args.save_checkpoint_path, config=ckpt_config)
-        callbacks.append(ckpoint_cb)
+        if device_num == 1 or (device_num > 1 and rank_id == 0):
+            ckpt_config = CheckpointConfig(save_checkpoint_steps=args.save_checkpoint_steps,
+                                           keep_checkpoint_max=args.save_checkpoint_num)
+            ckpoint_cb = ModelCheckpoint(prefix='transformer', directory=args.save_checkpoint_path, config=ckpt_config)
+            callbacks.append(ckpoint_cb)
 
     if args.enable_lossscale == "true":
         scale_manager = DynamicLossScaleManager(init_loss_scale=cfg.init_loss_scale_value,