cancel task if disconnect

app.py

@@ -19,6 +19,7 @@ import uvicorn
 from fastapi import FastAPI, Request
 from fastapi.responses import StreamingResponse
 from fastapi.staticfiles import StaticFiles
+from loguru import logger
 from metagpt.actions.action import Action
 from metagpt.actions.action_output import ActionOutput
 from metagpt.config import CONFIG
@@ -174,11 +175,25 @@ async def create_message(req_model: NewMsg, request: Request):
             qa_type=QueryAnswerType.Answer.value,
         )
 
-        tc_id = 0
+        task = None
+
+        async def stop_if_disconnect():
+            while not await request.is_disconnected():
+                await asyncio.sleep(1)
+
+            if task is None:
+                return
 
+            if not task.done():
+                task.cancel()
+                logger.info(f"cancel task {task}")
+
+        asyncio.create_task(stop_if_disconnect())
+
+        tc_id = 0
         while True:
             tc_id += 1
-            if request and await request.is_disconnected():
+            if await request.is_disconnected():
                 return
             think_result: RoleRun = await role.think()
             if not think_result:  # End of conversion
@@ -210,7 +225,7 @@ async def create_message(req_model: NewMsg, request: Request):
         yield answer.prompt + "\n\n"  # Notify the front-end that the message is complete.
     except Exception as ex:
         description = str(ex)
-        answer = f"```python\n\n{traceback.format_exc()}\n\n```"
+        answer = traceback.format_exc()
         step = ThinkActStep(
             id=tc_id,
             status="failed",