diff --git a/python/pipeline/operator.py b/python/pipeline/operator.py
index 29c37f2c64356bde8ae1e93635a7bff48424264c..0f34fc4336beb2be429cb7af3829e365cac8718d 100644
--- a/python/pipeline/operator.py
+++ b/python/pipeline/operator.py
@@ -197,7 +197,7 @@ class Op(object):
             threads.append(t)
         return threads
 
-    def init_op(self, concurrency_idx):
+    def init_op(self):
         pass
 
     def _run_preprocess(self, parsed_data, data_id, log_func):