TCP Transport RuntimeError with Python 3.13 + uvloop

TCP Transport RuntimeError with Python 3.13 + uvloop

Summary

uvloop is causing RuntimeError: unable to perform operation on <TCPTransport closed=True> errors when used with Python 3.13. Switching to --loop asyncio fixes the issue.

Environment

• Python: 3.13.3
• uvloop: (latest)
• Starlette: 0.46.2
• FastAPI: 0.115.14

Reproduction

1. Use Python 3.13
2. Run uvicorn with --loop uvloop
3. Make concurrent HTTP requests (e.g., browser loading static files)
4. Client disconnects/refreshes during response

Workaround

Use --loop asyncio instead of uvloop.

Expected

uvloop should handle closed connections gracefully like asyncio does.

Edit

I had a stray uvicorn process that had wracked up 9hrs of CPU time, this could potentially be the issue?

首先，使用 Python 3.13.3、uvloop 和 uvicorn，通过并发请求以及客户端断开连接或刷新来复现该故障；将其与 --loop asyncio 进行比较。跟踪 TCPTransport closed=True RuntimeError，并说明所报告的残留 uvicorn 进程。完成的标准是：在复现过程中，uvloop 配置能够处理已关闭的连接而不会出现此错误。