python runtime_error ai_generated true

RuntimeError: Event loop is closed

ID: python/starlette-event-loop-closed

Also available as: JSON · Markdown · 中文
80%Fix Rate
85%Confidence
0Evidence
2024-08-14First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
0.30+ active — — —

Root Cause

Async resources (e.g., aiohttp/httpx client, DB pool) created in one event loop are reused after that loop is closed, often across test cases or reloads.

generic

中文

在某个事件循环中创建的异步资源（如 aiohttp/httpx 客户端、数据库连接池）在该循环关闭后被复用，常见于测试用例或热重载。

Workarounds

  1. 92% success 
    from contextlib import asynccontextmanager
@asynccontextmanager
async def lifespan(app):
    app.state.client = httpx.AsyncClient()
    yield
    await app.state.client.aclose()
app = FastAPI(lifespan=lifespan)
  2. 90% success 
    async with httpx.AsyncClient() as client:
    r = await client.get(url)

Dead Ends

Common approaches that don't work:

  1. 80% fail

    Replaces loop but leaves stale client bound to old loop.

  2. 95% fail

    Buffering setting irrelevant to event loop lifecycle.