code optimized

Author: seiriosPlus

python/paddle/fluid/trainer.py

@@ -141,14 +141,10 @@ def __init__(self,
         self.chief = True
         self.checkpoint = checkpoint_config
         if self.checkpoint:
-            if not isinstance(self.checkpoint, CheckpointConfig):
-                raise TypeError(
-                    "The checkpoint_config shoule be an instance of CheckpointConfig"
-                )
-            else:
-                serial = io.get_latest_checkpoint_serial(
-                    self.checkpoint.checkpoint_dir)
-                self.checkpoint.load_serial = serial if serial >= 0 else None
+            assert isinstance(self.checkpoint, CheckpointConfig)
+            serial = io.get_latest_checkpoint_serial(
+                self.checkpoint.checkpoint_dir)
+            self.checkpoint.load_serial = serial if serial >= 0 else None
 
         self.scope = core.Scope()
 
@@ -385,8 +381,8 @@ def _train_by_any_executor(self, event_handler, exe, num_epochs, reader):
                 else:
                     metrics = exe.run(feed=data, fetch_list=[])
 
-                event_handler(EndStepEvent(epoch_id, step_id, metrics))
                 self._save_checkpoint(epoch_id, step_id)
+                event_handler(EndStepEvent(epoch_id, step_id, metrics))
             event_handler(EndEpochEvent(epoch_id))
         self._clean_checkpoint()