macOS 12 poll syscall returns prematurely

[MicroTransactionsMatterToo]

BPO	28087
Nosy	@gpshead, @ronaldoussoren, @ncoghlan, @vstinner, @rbtcollins, @ned-deily, @MicroTransactionsMatterToo
PRs	bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS. #462 [3.6] bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS #463 bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS. … #973 [3.5] bpo-28087: Skip test_asyncore and test_eintr poll failures on macOS #1424 bpo-28087: Detect broken poll() on macOS Sierra #1426 bpo-28087: Reenable poll() tests on macOS #1664
Files	buildlog.log: Build Log eintr_tester.diff issue28087.patch smime.p7s smime.p7s

^{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 2020-03-18.15:16:09.677>
created_at = <Date 2016-09-11.23:36:48.835>
labels = ['OS-mac', '3.7', 'tests']
title = 'macOS 12 poll syscall returns prematurely'
updated_at = <Date 2020-03-18.15:16:09.676>
user = 'https://github.com/MicroTransactionsMatterToo'

bugs.python.org fields:

activity = <Date 2020-03-18.15:16:09.676>
actor = 'vstinner'
assignee = 'none'
closed = True
closed_date = <Date 2020-03-18.15:16:09.677>
closer = 'vstinner'
components = ['macOS', 'Tests']
creation = <Date 2016-09-11.23:36:48.835>
creator = 'MicroTransactionsMatterToo'
dependencies = []
files = ['44569', '44572', '44575', '44576', '44577']
hgrepos = []
issue_num = 28087
keywords = ['patch']
message_count = 34.0
messages = ['275887', '275889', '275894', '275912', '275913', '275914', '275915', '275929', '275932', '278623', '288055', '288070', '290300', '290301', '291065', '291078', '291082', '291137', '292869', '292870', '292875', '292876', '293168', '293169', '293176', '293186', '293944', '293951', '294269', '294277', '294304', '294309', '300128', '364527']
nosy_count = 7.0
nosy_names = ['gregory.p.smith', 'ronaldoussoren', 'ncoghlan', 'vstinner', 'rbcollins', 'ned.deily', 'MicroTransactionsMatterToo']
pr_nums = ['462', '463', '973', '1424', '1426', '1664']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue28087'
versions = ['Python 2.7', 'Python 3.6', 'Python 3.7']

[MicroTransactionsMatterToo]

Upon calling the select.poll objects poll method with no file descriptors registered, it will return an empty list immediately, regardless of the timeout given. This is a problem in the Mac OS X kernels implementation of the poll syscall, but the test can be easily fixed by binding a throwaway socket to the poll objects, and then using the poll method as usual.

Build details are attached

[MicroTransactionsMatterToo]

Patch exemplifying a fix for this in the test files

[MicroTransactionsMatterToo]

Fixed patch file, now in diff format

[ned-deily]

Thanks for the report. This seems to be a problem visible in the public betas of the upcoming macOS 12 release, not in previous releases (10.11 and earlier). Do you know if the problem has been reported to Apple? Also, I've uploaded a reviewable version of your patch.

[MicroTransactionsMatterToo]

Apple doesn’t allow access to other peoples bug reports, so I couldn’t say whether it’s been reported.

Many Thanks,
Ennis Massey

Wet Ferret Studios <http://wet-ferret-studios.azurewebsites.net/\>

[ned-deily]

OK, if you get a chance, it would be helpful to submit a RADAR on it and update this issue. I neglected to mention that your patch does seem to work, e.g., test_eintr no longer fails.

[MicroTransactionsMatterToo]

Ok, cool

Many Thanks,
Ennis Massey

Wet Ferret Studios <http://wet-ferret-studios.azurewebsites.net/\>

[rbtcollins]

@ned - any objection to my committing this at this point?

[ned-deily]

I'm not sure it should be a permanent fix. Perhaps you could add the test decorator so that it is only tested on 10.12. I don't have time to look at it more myself before b1.