Subprocess on a GunicornWebWorker returns 255

[oux]

from aiohttp import web
import asyncio

app = web.Application()

async def ls():
    stdout = None
    proc = await asyncio.create_subprocess_shell(
        "ls",
        stdout=asyncio.subprocess.PIPE,
    )                                                                                                                                                                                                                                                          
    stdout, _ = await proc.communicate()
    print(f"return code: {proc.returncode}")

asyncio.run(ls())

I run this code in 3 ways:

poetry run gunicorn --worker-class aiohttp.GunicornUVLoopWebWorker test_subprocess:app

return code: 0

poetry run python test_subprocess.py

return code: 0

poetry run gunicorn --worker-class aiohttp.GunicornWebWorker test_subprocess:app

child process pid 339436 exit status already read: will report returncode 255
return code: 255

Workaround to get the right return code with aiohttp.GunicornWebWorker :
Add following line on the script:

asyncio.set_child_watcher(asyncio.FastChildWatcher())

Issue:
asyncio.FastChildWatcher() is marked deprecated and will be removed on python 3.14

[pajod]

Thanks for the quality report!
Related: aio-libs/aiohttp#7038