optimized checkpoint and save_model

python/paddle/fluid/io.py

@@ -489,9 +489,9 @@ CHECKPOINT_SEPARATOR = "_"
 
 
 def save_checkpoint(executor,
-                    checkpoint_dir=None,
-                    max_num_checkpoints=3,
-                    main_program=None):
+                    checkpoint_dir,
+                    main_program=None,
+                    max_num_checkpoints=3):
     """
     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
@@ -500,12 +500,11 @@ def save_checkpoint(executor,
 
     :param executor
     :param checkpoint_dir
-    :param max_num_checkpoints
-    :param save_interval_secs
     :param main_program
+    :param max_num_checkpoints
     """
     if checkpoint_dir is None:
-        checkpoint_dir = os.getcwd()
+        raise ValueError("The values of 'checkpoint_dir' should not be None")
 
     if not os.path.isdir(checkpoint_dir):
         os.makedirs(checkpoint_dir)
@@ -518,7 +517,7 @@ def save_checkpoint(executor,
     _lru_delete(checkpoint_dir, max_num_checkpoints)
 
 
-def load_checkpoint(executor, checkpoint_dir=None, main_program=None):
+def load_checkpoint(executor, checkpoint_dir, main_program=None):
     """
     Load checkpoint from a directory by executor,
     it will find  the most recent saved checkpoint file and load it auto.
@@ -529,7 +528,7 @@ def load_checkpoint(executor, checkpoint_dir=None, main_program=None):
     """
 
     if checkpoint_dir is None:
-        checkpoint_dir = os.getcwd()
+        raise ValueError("The values of 'checkpoint_dir' should not be None")
 
     serial = _get_lastest_checkpoint_dir(checkpoint_dir)
 
@@ -546,7 +545,7 @@ def clean_checkpoint(checkpoint_dir, delete_dir=False):
     delete_dir only works when the directory is empty, otherwise, OSError is raised.  
     """
     if checkpoint_dir is None:
-        checkpoint_dir = os.getcwd()
+        raise ValueError("The values of 'checkpoint_dir' should not be None")
     _lru_delete(checkpoint_dir, max_num_checkpoints=0)
 
     if delete_dir and not os.listdir(checkpoint_dir):