New submission from Michel Hidalgo <hid.mic...@gmail.com>:
asyncio.ProactorEventLoop uses a socket.socketpair and signal.set_wakeup_fd to wake up a loop that's polling I/O. However it does so with no consideration for file descriptors previously set (i.e. no signal number forwarding). Either by user code or by another instance of asyncio.ProactorEventLoop. The following snippet is enough for the above to cause the loop to hang forever: import asyncio import gc asyncio.set_event_loop(asyncio.ProactorEventLoop()) asyncio.set_event_loop(asyncio.ProactorEventLoop()) gc.collect() asyncio.get_event_loop().run_forever() The first asyncio.ProactorEventLoop instance sets a signal wakeup file descriptor on construction (see https://github.com/python/cpython/blob/187f76def8a5bd0af7ab512575cad30cfe624b05/Lib/asyncio/proactor_events.py#L632). The second instances does the same, dropping the file descriptor set by the first one (not good, not necessarily bad). When the garbage collector purges the first instance, signal wakeups are disabled completely (see https://github.com/python/cpython/blob/187f76def8a5bd0af7ab512575cad30cfe624b05/Lib/asyncio/proactor_events.py#L679). The loop cannot be interrupted with Ctrl+C anymore (bad). ---------- components: Windows, asyncio messages: 384979 nosy: asvetlov, hidmic, paul.moore, steve.dower, tim.golden, yselivanov, zach.ware priority: normal severity: normal status: open title: asyncio.ProactorEventLoop mishandles signal wakeup file descriptor type: behavior versions: Python 3.8 _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue42913> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
