bug fix and optimize

python/paddle/fluid/trainer.py

@@ -79,8 +79,9 @@ class CheckpointConfig(object):
         else:
             self.step_interval = step_interval
 
-        self.epoch_id = 0
-        self.step_id = 0
+        self._epoch_id = 0
+        self._step_id = 0
+        self._load_serial = None
 
 
 def check_and_get_place(place):
@@ -174,17 +175,17 @@ class Trainer(object):
             exe = executor.Executor(place)
             exe.run(self.startup_program)
 
-        if self.load_checkpoint_serial:
+        if self.checkpoint._load_serial:
             exe = executor.Executor(place)
             io.load_checkpoint(exe, self.checkpoint.checkpoint_dir,
-                               self.load_checkpoint_serial,
+                               self.checkpoint._load_serial,
                                self.startup_program)
 
             epoch_id, step_id = io.load_trainer_args(
                 self.checkpoint.checkpoint_dir, self.load_checkpoint_serial,
                 self.trainer_id, ["epoch_id", "step_id"])
-            self.checkpoint.epoch_id = int(epoch_id)
-            self.checkpoint.step_id = int(step_id)
+            self.checkpoint._epoch_id = int(epoch_id)
+            self.checkpoint._step_id = int(step_id)
 
         if param_path and os.path.isdir(param_path):
             # load params from param_path into scope
@@ -351,7 +352,7 @@ class Trainer(object):
     def _train_by_any_executor(self, event_handler, exe, num_epochs, reader):
         epochs = [
             epoch_id for epoch_id in range(num_epochs)
-            if epoch_id >= self.checkpoint.epoch_id
+            if epoch_id >= self.checkpoint._epoch_id
         ]
         for epoch_id in epochs:
             event_handler(BeginEpochEvent(epoch_id))
@@ -360,7 +361,8 @@ class Trainer(object):
                     self._clean_checkpoint()
                     return
 
-                if self.checkpoint and self.checkpoint.step_id >= step_id and self.checkpoint.epoch_id == epoch_id:
+                if self.checkpoint and self.checkpoint._load_serial \
+                    and self.checkpoint._step_id >= step_id and self.checkpoint._epoch_id == epoch_id:
                     continue
 
                 begin_event = BeginStepEvent(epoch_id, step_id)