diff --git a/main.py b/main.py
index 523e88f..4338b70 100644
--- a/main.py
+++ b/main.py
@@ -35,6 +35,8 @@ if not os.path.exists(tmpDir):
 
 app = FastAPI()
 
+lock_simulation = asyncio.Lock()
+
 app.add_middleware(GZipMiddleware, minimum_size=1000)
 
 ############################################################
@@ -146,20 +148,18 @@ async def fastapi_dump_inp(network: str, inp: str) -> bool:
     dump_inp(network, inp)
     return True
 
-app.state.lock_simulation = False
-
 # 必须用这个PlainTextResponse，不然每个key都有引号
 @app.get("/runproject/", response_class = PlainTextResponse)
 async def fastapi_run_project(network: str) -> str:
-    print(app.state.lock_simulation)
-    if app.state.lock_simulation:
+    global lock_simulation
+    
+    if lock_simulation.locked:
         raise HTTPException(status_code=409, detail="is in simulation")   
-
-    app.state.lock_simulation = True
-    print('lock simulation')
-    result = run_project(network)
-    app.state.lock_simulation = False
-    return result
+    
+    async with lock_simulation:
+        print('lock simulation')
+        result = run_project(network)
+        return result
         
 # put in inp folder, name without extension
 @app.get("/runinp/")