test_bufio failures on Win64 buildbot

[pitrou]

BPO	15192
Nosy	@pitrou, @jkloth, @zware, @serhiy-storchaka

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2020-04-27.04:39:40.103>
created_at = <Date 2012-06-26.12:53:28.725>
labels = ['type-bug', 'tests']
title = 'test_bufio failures on Win64 buildbot'
updated_at = <Date 2020-04-27.04:39:40.102>
user = 'https://github.com/pitrou'

bugs.python.org fields:

activity = <Date 2020-04-27.04:39:40.102>
actor = 'zach.ware'
assignee = 'none'
closed = True
closed_date = <Date 2020-04-27.04:39:40.103>
closer = 'zach.ware'
components = ['Tests']
creation = <Date 2012-06-26.12:53:28.725>
creator = 'pitrou'
dependencies = []
files = []
hgrepos = []
issue_num = 15192
keywords = ['buildbot']
message_count = 7.0
messages = ['164072', '164083', '164084', '164086', '164095', '331681', '367392']
nosy_count = 5.0
nosy_names = ['pitrou', 'jkloth', 'jeremy.kloth', 'zach.ware', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'out of date'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue15192'
versions = ['Python 2.7', 'Python 3.2', 'Python 3.3']

[pitrou]

test_bufio fails sporadically on the AMD64 Windows7 SP1 buildbot, e.g.:

http://buildbot.python.org/all/builders/AMD64%20Windows7%20SP1%203.x/builds/161/steps/test/logs/stdio

test_nullpat (test.test_bufio.CBufferSizeTest) ... ok
test_primepat (test.test_bufio.CBufferSizeTest) ... ERROR
test_nullpat (test.test_bufio.PyBufferSizeTest) ... ok
test_primepat (test.test_bufio.PyBufferSizeTest) ... ok

======================================================================
ERROR: test_primepat (test.test_bufio.CBufferSizeTest)
----------------------------------------------------------------------

Traceback (most recent call last):
  File "C:\Users\Buildbot\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_bufio.py", line 59, in test_primepat
    self.drive_one(b"1234567890\00\01\02\03\04\05\06")
  File "C:\Users\Buildbot\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_bufio.py", line 52, in drive_one
    self.try_one(teststring)
  File "C:\Users\Buildbot\buildbot.python.org\3.x.kloth-win64\build\lib\test\test_bufio.py", line 20, in try_one
    support.unlink(support.TESTFN)
  File "C:\Users\Buildbot\buildbot.python.org\3.x.kloth-win64\build\lib\test\support.py", line 229, in unlink
    os.unlink(filename)
PermissionError: [Error 5] Access is denied: '@test_2420_tmp'

Is there some kind of anti-virus installed on the machine?

[skrah]

Looks similar to the sporadic test_reprlib failure. Roumen has explained
that here:

http://bugs.python.org/issue14599#msg162727

I didn't test myself though, just a guess.

[pitrou]

Looks similar to the sporadic test_reprlib failure. Roumen has explained
that here:

I don't think there's anything similar. The path is much smaller in
test_bufio.

[jeremykloth]

I've changed the malware scanner to disable real-time protection and
have disabled scanning of the buildbot directories.

Note that I could reproduce intermittent failures when using '-j' of
regrtest, but with these changes they no longer appear.

[pitrou]

I've changed the malware scanner to disable real-time protection and
have disabled scanning of the buildbot directories.

Thank you. I hope that, thanks to this change, we later can make the
Win64 buildbot part of the bunch of stable buildbots.

[serhiy-storchaka]

The implementation of test.support.unlink() was changed since. It tries to change permissions of read-only files, and repeat attempts several times. It looks more reliable now. Is this issue still reproducible?

[zware]

I've not seen this issue on that worker for a very long time; closing the issue.