bug fix

python/paddle/fluid/trainer.py

@@ -139,13 +139,14 @@ class Trainer(object):
         self.trainer_id = 0
         self.chief = True
         self.checkpoint = checkpoint_config
-        if self.checkpoint and \
-            not isinstance(self.checkpoint, CheckpointConfig):
-            raise TypeError(
-                "The checkpoint_config shoule be an instance of CheckpointConfig"
-            )
-        self.checkpoint._load_serial = io.need_load_checkpoint(
-            self.checkpoint.checkpoint_dir)
+        if self.checkpoint:
+            if not isinstance(self.checkpoint, CheckpointConfig):
+                raise TypeError(
+                    "The checkpoint_config shoule be an instance of CheckpointConfig"
+                )
+            else:
+                self.checkpoint._load_serial = io.need_load_checkpoint(
+                    self.checkpoint.checkpoint_dir)
 
         self.scope = core.Scope()
 
@@ -175,7 +176,7 @@ class Trainer(object):
             exe = executor.Executor(place)
             exe.run(self.startup_program)
 
-        if self.checkpoint._load_serial:
+        if self.checkpoint and self.checkpoint._load_serial:
             exe = executor.Executor(place)
             io.load_checkpoint(exe, self.checkpoint.checkpoint_dir,
                                self.checkpoint._load_serial,