New submission from STINNER Victor:
I noticed the following warning in test_asyncio (see above). It understand that
when the asyncio Future ("destination" in _chain_future) is cancelled,
_call_check_cancel() calls source_loop.call_soon_threadsafe(source.cancel)
where source is a concurrent.futures.Future object.
Then futures.Future.cancel() calls self._invoke_callbacks() which calls
_call_set_state() of _chain_future(). _call_set_state() calls
dest_loop.call_soon_threadsafe(_set_state, destination, source) but at this
point, the event loop is closed. Morever, destination (the asyncio future) is
already cancelled, but it doesn't make sense to try to copy the state: source
and destination are already cancelled.
I suggest to modify _call_set_state() to do nothing if destination is already
cancelled:
def _call_set_state(source):
if destination.cancelled():
return
(...)
*But* I see that futures.Future has a set_running_or_notify_cancel() method
which seems to be important to call. Maybe we should call it in this case?
def _call_set_state(source):
if destination.cancelled():
source.set_running_or_notify_cancel()
return
(...)
--
The warning:
http://buildbot.python.org/all/builders/AMD64%20Windows8%203.6/builds/43/steps/test/logs/stdio
test_sock_sendall
(test.test_asyncio.test_selector_events.BaseSelectorEventLoopTests) ...
exception calling callback for <Future at 0xec840d1e28 state=finished returned
NoneType>
Traceback (most recent call last):
File "D:\buildarea\3.6.bolen-windows8\build\lib\concurrent\futures\_base.py",
line 297, in _invoke_callbacks
callback(self)
File "D:\buildarea\3.6.bolen-windows8\build\lib\asyncio\futures.py", line
462, in _call_set_state
dest_loop.call_soon_threadsafe(_set_state, destination, source)
File "D:\buildarea\3.6.bolen-windows8\build\lib\asyncio\base_events.py", line
603, in call_soon_threadsafe
handle = self._call_soon(callback, args)
File "D:\buildarea\3.6.bolen-windows8\build\lib\asyncio\base_events.py", line
577, in _call_soon
self._check_closed()
File "D:\buildarea\3.6.bolen-windows8\build\lib\asyncio\base_events.py", line
356, in _check_closed
raise RuntimeError('Event loop is closed')
RuntimeError: Event loop is closed
ok
----------
components: asyncio
messages: 277107
nosy: gvanrossum, haypo, yselivanov
priority: normal
severity: normal
status: open
title: asyncio: wrap_future() doesn't handle cancellation correctly
versions: Python 3.5, Python 3.6, Python 3.7
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Python tracker <[email protected]>
<http://bugs.python.org/issue28232>
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