test_stack_overflow (test.test_faulthandler.FaultHandlerTests) is stuck with GCC10

[marxin]

BPO	38965
Nosy	@vstinner, @ned-deily, @mcepl, @stratakis, @miss-islington, @marxin
PRs	bpo-38965: Fix stuck in test_stack_overflow tests. #17462 bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 #17467 [3.7] bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467) #17468 [3.8] bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467) #17469 [3.6] bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467) #28079

^{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 2019-12-04.20:14:09.520>
created_at = <Date 2019-12-04.08:33:20.966>
labels = ['3.7', '3.8', 'type-bug', 'tests', '3.9']
title = 'test_stack_overflow (test.test_faulthandler.FaultHandlerTests) is stuck with GCC10'
updated_at = <Date 2021-08-31.06:30:47.466>
user = 'https://github.com/marxin'

bugs.python.org fields:

activity = <Date 2021-08-31.06:30:47.466>
actor = 'ned.deily'
assignee = 'none'
closed = True
closed_date = <Date 2019-12-04.20:14:09.520>
closer = 'vstinner'
components = ['Tests']
creation = <Date 2019-12-04.08:33:20.966>
creator = 'Martin Li\xc5\xa1ka'
dependencies = []
files = []
hgrepos = []
issue_num = 38965
keywords = ['patch']
message_count = 11.0
messages = ['357778', '357824', '357825', '357826', '357827', '357828', '357943', '357950', '376264', '400692', '400693']
nosy_count = 6.0
nosy_names = ['vstinner', 'ned.deily', 'mcepl', 'cstratak', 'miss-islington', 'Martin Li\xc5\xa1ka']
pr_nums = ['17462', '17467', '17468', '17469', '28079']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue38965'
versions = ['Python 3.6', 'Python 3.7', 'Python 3.8', 'Python 3.9']

[marxin]

The test-case is stuck after update to GCC 10.
I've got a patch for that.

[vstinner]

New changeset 8b78796 by Victor Stinner in branch 'master':
bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467)
8b78796

[vstinner]

Thanks Martin Liška for the bug report and your PR 17462!

I chose to use volatile instead, since it's already the second time that we have to fix this function for a specific compiler. You abandonned your PR and confrmed that my PR fix your issue with GCC 10, so I merged my PR. Thanks for testing ;-)

I backported the fix to 3.7 and 3.8 branches.

[vstinner]

The cool thing is that GCC now also implements tail call optimization!

[miss-islington]

New changeset 5044c88 by Miss Islington (bot) in branch '3.7':
bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467)
5044c88

[miss-islington]

New changeset f4a21d3 by Miss Islington (bot) in branch '3.8':
bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467)
f4a21d3

[stratakis]

Would it make sense to also backport this fix to the 3.6 release?

People compiling 3.6 with gcc 10 will stumble upon that.

[vstinner]

Would it make sense to also backport this fix to the 3.6 release?

Sadly, 3.6 no longer accept bugfixes:
https://devguide.python.org/#status-of-python-branches

[mcepl]

3.7 patch applies cleanly even for 3.6.12.

[ned-deily]

New changeset 8934bb0 by Miss Islington (bot) in branch '3.6':
bpo-38965: Fix faulthandler._stack_overflow() on GCC 10 (GH-17467) (GH-28079)
8934bb0

[ned-deily]

I decided to also backport this fix for 3.6.15 since the problem causes test hangs when using GCC 10, as is now that case on one of my test machines. Note that the devguide says: "You should also consider fixing hard-failing tests in open security branches since it is important to be able to run the tests successfully before releasing."

https://devguide.python.org/devcycle/#security-branches