select_selector_crash.py

import socket
import asyncio
import selectors


async def wait_readable(s):
    event = asyncio.Event()
    loop = asyncio.get_running_loop()
    loop.add_reader(s, event.set)
    try:
        await event.wait()
    finally:
        loop.remove_reader(s)


async def main():
    class _Done(Exception):
        pass

    s1, s2 = socket.socketpair()
    with s1, s2:
        s1.setblocking(False)
        s2.setblocking(False)
        try:
            async with asyncio.TaskGroup() as tg:
                tg.create_task(wait_readable(s2))
                await asyncio.sleep(1)
                s2.close()
                await asyncio.sleep(1)
                raise _Done
        except* _Done:
            pass

    return False
    s1, s2 = socket.socketpair()
    with s1, s2:
        s1.setblocking(False)
        s2.setblocking(False)
        s1.send(b"\x00")
        await wait_readable(s2)


asyncio.run(
    main(),
    loop_factory=lambda: asyncio.SelectorEventLoop(selector=selectors.SelectSelector()),
)