diff --git a/api/core/workflow/graph_engine/graph_engine.py b/api/core/workflow/graph_engine/graph_engine.py
index 3bb96a619f..cf3ccf387d 100644
--- a/api/core/workflow/graph_engine/graph_engine.py
+++ b/api/core/workflow/graph_engine/graph_engine.py
@@ -1,9 +1,8 @@
-from concurrent.futures import ThreadPoolExecutor, wait
 import logging
 import queue
-import threading
 import time
 from collections.abc import Generator, Mapping
+from concurrent.futures import ThreadPoolExecutor, wait
 from typing import Any, Optional
 
 from flask import Flask, current_app