diff --git a/vdb/milvus.py b/vdb/milvus.py
index 4719c53..7b1f35f 100644
--- a/vdb/milvus.py
+++ b/vdb/milvus.py
@@ -1,6 +1,7 @@
 import os
 from appPublic.jsonConfig import getConfig
 from appPublic.log import debug, exception, error
+from threading import Lock
 
 from pymilvus import (
 	connections, FieldSchema, CollectionSchema,