fix data_feeder bug

paddlehub/finetune/task/base_task.py

@@ -836,9 +836,16 @@ class BaseTask(object):
         global_run_states = []
         period_run_states = []
 
+        parallel_batch = []
         for run_step, batch in enumerate(self.reader(), start=1):
-            if self.config.use_data_parallel and len(batch) < self.device_count:
-                continue
+            if self.config.use_data_parallel:
+                parallel_batch += batch
+                if len(parallel_batch) < self.device_count:
+                    continue
+                else:
+                    batch = parallel_batch
+                    parallel_batch = []
+
             step_run_state = RunState(len(self.fetch_list))
             step_run_state.run_step = 1
             num_batch_examples = len(batch)