[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
STINNER Victor added the comment: Le lundi 29 juin 2015, Yury Selivanov rep...@bugs.python.org a écrit : You should develop using asyncio debug mode: Maybe we should promote this check to the production mode? asyncio must be slow. The check has a cost, I prefer to keep it only in debug mode. It's probably more a doc issue. We should maybe repeat the info at the beginning of the asyncio doc. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24532 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
New submission from Марк Коренберг:
Suppose that program:
import asyncio
import socket
def receiver(loop):
(a, b) = socket.socketpair()
loop.call_later(1, lambda: print('Should be called inside the loop'))
end = loop.time() + 3
print('Starting busy receiver')
while loop.time() end:
a.send(b'test')
yield from loop.sock_recv(b, 65536)
# yield from asyncio.sleep(0) # =
print('Busy receiver complete')
# just not to stop ioloop immediatelly
yield from asyncio.sleep(0.5)
def main():
loop = asyncio.get_event_loop()
loop.run_until_complete(receiver(loop))
loop.close()
if __name__ == '__main__':
main()
Without asyncio.sleep(0) it will not fire time-delayed calls! If I add
asyncio.sleep(0), everything work right. As I think, It is because recv()
syscall is always succeeded, and we never return to ioloop (to epoll() I mean).
In other words, it is classical `reader starvation` as mentioned in man epoll.
It is not documented, that this function may block event loop, in spite of it
returns coroutine! I thought that this function will setup EPOLLIN event for
socket's FD + call recv() after that. I spent many time to debug program.
--
components: asyncio
messages: 245952
nosy: gvanrossum, haypo, mmarkk, yselivanov
priority: normal
severity: normal
status: open
title: asyncio.sock_recv() blocks normal ioloop actions.
type: behavior
versions: Python 3.4
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[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
STINNER Victor added the comment: You should develop using asyncio debug mode: https://docs.python.org/dev/library/asyncio-dev.html#asyncio-dev haypo@selma$ PYTHONASYNCIODEBUG=1 ./python x.py Starting busy receiver Traceback (most recent call last): File x.py, line 21, in module main() File x.py, line 18, in main loop.run_until_complete(receiver(loop)) File /home/haypo/prog/python/default/Lib/asyncio/base_events.py, line 341, in run_until_complete return future.result() File /home/haypo/prog/python/default/Lib/asyncio/futures.py, line 276, in result raise self._exception File /home/haypo/prog/python/default/Lib/asyncio/tasks.py, line 238, in _step result = coro.send(value) File x.py, line 11, in receiver yield from loop.sock_recv(b, 65536) File /home/haypo/prog/python/default/Lib/asyncio/selector_events.py, line 316, in sock_recv raise ValueError(the socket must be non-blocking) ValueError: the socket must be non-blocking /home/haypo/prog/python/default/Lib/asyncio/base_events.py:384: ResourceWarning: unclosed event loop _UnixSelectorEventLoop running=False closed=False debug=True sys:1: ResourceWarning: unclosed socket object at 0x7f0b03d7d688 sys:1: ResourceWarning: unclosed socket object at 0x7f0b03d7d5f8 -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24532 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
Марк Коренберг added the comment: $ PYTHONASYNCIODEBUG=1 ./bug.py Starting busy receiver Busy receiver complete Executing Task pending coro=receiver() running at ./bug.py:16 wait_for=Future pending cb=[Task._wakeup()] created at /usr/lib/python3.4/asyncio/tasks.py:490 cb=[_run_until_complete_cb() at /usr/lib/python3.4/asyncio/base_events.py:123] created at /usr/lib/python3.4/asyncio/base_events.py:296 took 3.001 seconds Should be called inside the loop -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24532 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
Марк Коренберг added the comment: Adding of b.setblocking(0) after socketpair() does not help. -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24532 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue24532] asyncio.sock_recv() blocks normal ioloop actions.
Yury Selivanov added the comment: You should develop using asyncio debug mode: Maybe we should promote this check to the production mode? -- ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue24532 ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
