python runtime_error ai_generated true

TimeoutError: The read operation timed out (after 30s) while handling concurrent requests

ID: python/fastapi-async-def-blocking-call

Also available as: JSON · Markdown · 中文
80%Fix Rate
87%Confidence
0Evidence
2024-08-21First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
0.100+ active — — —

Root Cause

A blocking call (e.g., `requests.get`, `time.sleep`, synchronous DB driver) inside an `async def` endpoint blocks the event loop, starving other requests.

generic

中文

`async def` 端点中的阻塞调用（如 `requests.get`、`time.sleep`、同步数据库驱动）阻塞了事件循环，导致其他请求饥饿。

Workarounds

  1. 93% success 
    from fastapi.concurrency import run_in_threadpool
result = await run_in_threadpool(requests.get, url)
  2. 95% success 
    async with httpx.AsyncClient() as c:
    r = await c.get(url)

Dead Ends

Common approaches that don't work:

  1. 75% fail

    Delays symptom; event loop still blocked.

  2. 70% fail

    Each worker still blocks on the same call.