fix save_pretrained & load_checkpoint bug in DDP mode

Link: https://code.alibaba-inc.com/Ali-MaaS/MaaS-lib/codereview/11012439

    * fix save_pretrained & load_checkpoint bug in DDP mode

modelscope/trainers/hooks/checkpoint_hook.py

@@ -215,6 +215,10 @@ class CheckpointHook(Hook):
             # TODO a temp fix to avoid pipeline_name and task mismatch
             config['pipeline'] = {'type': config['task']}
 
+        # remove parallel module that is not JSON serializable
+        if 'parallel' in config and 'module' in config['parallel']:
+            del config['parallel']['module']
+
         class SaveConfig:
 
             def __init__(self, output_dir, config):
@@ -422,4 +426,5 @@ class BestCkptSaverHook(CheckpointHook):
 
     def after_run(self, trainer):
         if self.restore_best:
-            self.load_checkpoint(self._best_ckpt_file, trainer)
+            if is_master():
+                self.load_checkpoint(self._best_ckpt_file, trainer)