Bug report

So, I've updated python from 3.11.0 to 3.11.1 and one of my utilities which runs a lot of external processes withasyncio.create_subprocess_exec started failing in different places in weird ways. It turned out that with some probabilityasyncio.subprocess.Process.communicate() would now return an empty stdout. Here's a repro:

import asyncioasync def main():    attempt = 1    while True:        proc = await asyncio.create_subprocess_exec('/bin/echo', 'test', stdout=asyncio.subprocess.PIPE, stderr=asyncio.subprocess.PIPE)        stdout, stderr = await proc.communicate()        text = stdout.decode('utf-8').strip()        if text != 'test':            raise RuntimeError(f'FAIL on attempt {attempt}: output="{text}"')        attempt += 1asyncio.run(main())

You may have to wait somewhat for the problem to reproduce, but for me it fails in under 15 seconds more or less reliably. Possible output:

RuntimeError: FAIL on attempt 3823: output=""

Your environment

• CPython versions tested on: 3.11.1
• Operating system and architecture: FreeBSD 13.1 amd64

Linked PRs

• GH-100133: fixasyncio subprocess losingstderr andstdout output #100154
• [3.11] GH-100133: fixasyncio subprocess losingstderr andstdout output (GH-100154) #100398