[issue21998] asyncio: a new self-pipe should be created in the child process after fork

[STINNER Victor]

New submission from STINNER Victor:

It looks like asyncio does not suppport fork() currently: on fork(), the event loop of the parent and the child process share the same "self pipe".

Example:
---
import asyncio, os
loop = asyncio.get_event_loop()
pid = os.fork()
if pid:
    print("parent", loop._csock.fileno(), loop._ssock.fileno())
else:
    print("child", loop._csock.fileno(), loop._ssock.fileno())
---

Output:
---
parent 6 5
child 6 5
---

I'm not sure that it's revelant to use asyncio with fork, but I wanted to open an issue at least as a reminder.

I found the "self pipe" + fork issue when reading the issue #12060, while working on a fix for the signal handling race condition on FreeBSD: issue #21645.

----------
components: asyncio
messages: 223344
nosy: gvanrossum, haypo, yselivanov
priority: normal
severity: normal
status: open
title: asyncio: a new self-pipe should be created in the child process after fork
versions: Python 3.4, Python 3.5

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue21998>
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