bug fix

python/paddle/fluid/io.py

@@ -472,8 +472,7 @@ def save_checkpoint(executor,
                     main_program=None,
                     max_num_checkpoints=3,
                     lookup_table=None,
-                    ps_endpoint_list=None
-                    ):
+                    ps_endpoint_list=None):
     """
     Save Checkpoint will save persistable LodTensor variables from main_program in checkpoint directory,
     the directory named by serial number from 0 to (n -1), save_checkpoint use LRU strategy
@@ -495,14 +494,18 @@ def save_checkpoint(executor,
     if not os.path.isdir(checkpoint_dir):
         os.makedirs(checkpoint_dir)
 
+    is_chief = trainer_id == 0
+
     serial = get_latest_checkpoint_serial(checkpoint_dir) + 1
     cur_dir = _get_serial_dir(checkpoint_dir, serial)
 
     save_trainer_args(cur_dir, trainer_id, trainer_args)
 
-    if trainer_id == 0:
+    if is_chief:
         save_persist_vars_without_grad(executor, cur_dir, main_program)
-        save_pserver_vars_by_notify(executor, cur_dir, lookup_table, ps_endpoint_list)
+    if is_chief and lookup_table and ps_endpoint_list:
+        save_pserver_vars_by_notify(executor, cur_dir, lookup_table,
+                                    ps_endpoint_list)
 
     _scroll_delete(checkpoint_dir, max_num_checkpoints)
 
@@ -618,7 +621,8 @@ def save_persist_vars_without_grad(executor, dirname, program):
     _write_success(cur_dir)
 
 
-def save_pserver_vars_by_notify(executor, dirname, lookup_table, ps_endpoint_list):
+def save_pserver_vars_by_notify(executor, dirname, lookup_table,
+                                ps_endpoint_list):
     """
     """
     cur_dir = _get_lookuptable_dir(dirname)
@@ -802,4 +806,3 @@ def get_latest_checkpoint_serial(checkpoint_dir):
         if success_num > current_dir:
             current_dir = success_num
     return current_dir
-