New submission from Ryder Lewis: Intermittently, when using asyncio.wait_for() with asyncio.open_connection() to cancel the open_connection() task after a timeout period, an asyncio.futures.InvalidStateError is raised. It seems to be a race condition, if the open_connection() call succeeds roughly at the same time as the timeout.
In order to recreate this issue, I used a slightly-modified version of the example at https://docs.python.org/3.4/library/asyncio-stream.html?highlight=open_connection#example ==== example.py ==== import asyncio import urllib.parse import sys @asyncio.coroutine def print_http_headers(url, timeout): url = urllib.parse.urlsplit(url) try: reader, writer = yield from asyncio.wait_for(asyncio.open_connection(url.hostname, 80), timeout) except asyncio.TimeoutError: print('Timed out with {}-second timeout'.format(timeout)) return query = ('HEAD {url.path} HTTP/1.0\r\n' 'Host: {url.hostname}\r\n' '\r\n').format(url=url) writer.write(query.encode('latin-1')) while True: line = yield from reader.readline() if not line: break line = line.decode('latin1').rstrip() if line: print('HTTP header> %s' % line) print('Success with {}-second timeout'.format(timeout)) url = sys.argv[1] loop = asyncio.get_event_loop() for timeout in range(5, 0, -1): task = asyncio.async(print_http_headers(url, timeout/100)) loop.run_until_complete(task) loop.close() ==== Output of "./example.py http://www.yahoo.com/"; after running multiple times ==== HTTP header> HTTP/1.0 301 Redirect HTTP header> Date: Tue, 06 May 2014 18:07:43 GMT HTTP header> Connection: close HTTP header> Via: http/1.1 ir12.fp.ne1.yahoo.com (ApacheTrafficServer/4.0.2) HTTP header> Server: ATS HTTP header> Cache-Control: no-store HTTP header> Content-Type: text/html; charset=utf-8 HTTP header> Content-Language: en HTTP header> Location: https://www.yahoo.com/ HTTP header> Content-Length: 214 Success with 0.04-second timeout Timed out with 0.03-second timeout Timed out with 0.02-second timeout Exception in callback <bound method Future.set_result of Future<CANCELLED>>(None,) handle: Handle(<bound method Future.set_result of Future<CANCELLED>>, (None,)) Traceback (most recent call last): File "/opt/python3/lib/python3.4/asyncio/events.py", line 39, in _run self._callback(*self._args) File "/opt/python3/lib/python3.4/asyncio/futures.py", line 298, in set_result raise InvalidStateError('{}: {!r}'.format(self._state, self)) asyncio.futures.InvalidStateError: CANCELLED: Future<CANCELLED> Timed out with 0.01-second timeout ---------- components: IO messages: 217999 nosy: ryder.lewis priority: normal severity: normal status: open title: Intermittent asyncio.open_connection / futures.InvalidStateError type: behavior versions: Python 3.4 _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue21447> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
