STINNER Victor added the comment:
Buildbots are happy, I close the issue.
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resolution: - fixed
status: open - closed
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Python tracker rep...@bugs.python.org
http://bugs.python.org/issue20452
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New submission from STINNER Victor:
The failure is minor, it's just a suboptimal code. Calling _run_once() 4 times
instead of 3.
http://buildbot.python.org/all/builders/x86%20Ubuntu%20Shared%203.x/builds/9630/steps/test/logs/stdio
Roundup Robot added the comment:
New changeset 5545634d98a1 by Victor Stinner in branch 'default':
Issue #20452: add more info in case of test_asyncio failure to try to debug the
http://hg.python.org/cpython/rev/5545634d98a1
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nosy: +python-dev
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STINNER Victor added the comment:
_run_once() can be called more than expected if selector.select() was
interrupted by a signal or because the granularity is wrong. If we want to
avoid that, a simple fix is just to loop again in this case. Attached patch
implements that (I wrote it for Tulip,
Roundup Robot added the comment:
New changeset 83e110399f3c by Victor Stinner in branch 'default':
Issue #20452: Oops, fix debug code :-/
http://hg.python.org/cpython/rev/83e110399f3c
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Python tracker rep...@bugs.python.org
STINNER Victor added the comment:
It looks like select() and poll() in Linux 2.6.28 has a resolution of 1/HZ,
where HZ can be retrieved from os.sysconf('SC_CLK_TCK'). Since Linux 2.6.28,
hrtimers are now used for timeouts.
High- (but not too high-) resolution timeouts
STINNER Victor added the comment:
Platform of x86 Ubuntu Shared 3.x buildbot:
Linux-2.6.31.5-linode21-i686-with-debian-lenny-sid little-endian, so a Linux
kernel 2.6.31.
It looks common on this buildbot that selector.select(timeout) takes less
timeout seconds (without returning any event).
Charles-François Natali added the comment:
It looks like select() and poll() in Linux 2.6.28 has a resolution
of 1/HZ, where HZ can be retrieved from os.sysconf('SC_CLK_TCK'). Since
Linux 2.6.28, hrtimers are now used for timeouts.
Attached patch improves the resolution field of
STINNER Victor added the comment:
Just round the timeout away from 0 and be happy: this will fix the busy-wait
problem, and that's all we want.
I didn't work, see:
http://bugs.python.org/issue20311#msg208601
Once again, I know I keep repeating myself, but having select/epoll/whatever
STINNER Victor added the comment:
More debug info on a new failure: test_timeout_rounding failed because once
EPollSelector.select(timeout=0.0099) took dt=0.0086 seconds. dt-timeout=-0.0014
and dt+granularity timeout is False (granularity=0.001, 1 millisecond).
* Buildbot: x86 Gentoo
Roundup Robot added the comment:
New changeset 827d948ac6aa by Victor Stinner in branch 'default':
Issue #20452: select and selectors round (again) timeout away from zero for
http://hg.python.org/cpython/rev/827d948ac6aa
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Python tracker
STINNER Victor added the comment:
New changeset 827d948ac6aa by Victor Stinner in branch 'default':
Issue #20452: select and selectors round (again) timeout away from zero
Let's test Charles-Francois option.
test_timeout_rounding failed because once
EPollSelector.select(timeout=0.0099)
STINNER Victor added the comment:
Results on x86 Gentoo 3.x buildbot:
[136/389] test_asyncio
WARNING: selector.select(timeout=0.09997069113887846470) took
dt=0.09961039200425148010 sec (dt-timeout=-0.00036029913462698460)
WARNING: dt+0.0012 timeout? True
WARNING:
Roundup Robot added the comment:
New changeset 21aa1a224049 by Victor Stinner in branch 'default':
Issue #20452: Remove debug code, no more needed
http://hg.python.org/cpython/rev/21aa1a224049
New changeset f9a09b40bc17 by Victor Stinner in branch 'default':
Issue #20311, #20452: poll and epoll
STINNER Victor added the comment:
Summary of this issue:
- test_asyncio was still failing because BaseEventLoop._granularity was not
enough to round correctly timeouts, deadlines and times. poll/epoll rounded
towards zero, whereas asyncio rounds away from zero. So the maximum difference
in
STINNER Victor added the comment:
Oh, another question: should I reopen the issue #20320 (round timeout in select
and kqueue)?
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Python tracker rep...@bugs.python.org
http://bugs.python.org/issue20452
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STINNER Victor added the comment:
Oops, I mentionned the wrong issue number in the following commits. There were
related to this issue (#20452):
New changeset 8fc69d43bc49 by Victor Stinner in branch 'default':
Issue #20455: math.ceil() returns an int in Python 3, no need to cast the
Roundup Robot added the comment:
New changeset 7f649ff0756c by Victor Stinner in branch 'default':
Issue #20452: test_asyncio: Add more info if the test fails
http://hg.python.org/cpython/rev/7f649ff0756c
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Python tracker rep...@bugs.python.org
STINNER Victor added the comment:
There is a similar (but different?) issue on Windows XP. I tried to fix it with
the 4 last commits.
The test uses a busy loop. The scheduled handle is called after 0.100 -
granularity. The granularity is usually 15.6 ms on Windows, so the expected
mimiumum
STINNER Victor added the comment:
Debug info on the Windows failure:
* The busy loop took 89.99 ms
* time.motononic() (which is GetTickCount64()) has a resolution of 10.0144 ms
http://buildbot.python.org/all/builders/x86%20Windows7%203.x/builds/7948/steps/test/logs/stdio
Roundup Robot added the comment:
New changeset a090804862f8 by Victor Stinner in branch 'default':
Issue #20452: test_asyncio checks also the granularity
http://hg.python.org/cpython/rev/a090804862f8
New changeset 60a960434e5c by Victor Stinner in branch 'default':
Issue #20452: Fix
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