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test_bad_getattr crashes on APPX test #84638
Description
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 = 'https://github.com/zooba'
closed_at = <Date 2020-09-24.20:39:51.631>
created_at = <Date 2020-04-30.23:10:27.627>
labels = ['3.8', 'OS-windows', 'type-crash', '3.9']
title = 'test_bad_getattr crashes on APPX test'
updated_at = <Date 2020-09-24.20:39:51.631>
user = 'https://github.com/zooba'bugs.python.org fields:
activity = <Date 2020-09-24.20:39:51.631>
actor = 'steve.dower'
assignee = 'steve.dower'
closed = True
closed_date = <Date 2020-09-24.20:39:51.631>
closer = 'steve.dower'
components = ['Windows']
creation = <Date 2020-04-30.23:10:27.627>
creator = 'steve.dower'
dependencies = []
files = []
hgrepos = []
issue_num = 40458
keywords = ['patch']
message_count = 8.0
messages = ['367803', '367880', '367881', '367888', '368060', '368185', '368186', '368189']
nosy_count = 7.0
nosy_names = ['paul.moore', 'vstinner', 'tim.golden', 'lukasz.langa', 'zach.ware', 'steve.dower', 'miss-islington']
pr_nums = ['19845', '19941']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'crash'
url = 'https://bugs.python.org/issue40458'
versions = ['Python 3.8', 'Python 3.9']
Activity
zooba commentedon Apr 30, 2020
The Windows CI machines on Azure Pipelines run additional tests to check an "installed" layout and with the UWP entry point that's used for the Windows Store package.
These tests have been failing intermittently (though regularly) with a stack overflow crash in the PyPickler tests.
Example: https://dev.azure.com/Python/cpython/_build/results?buildId=62055&view=results
test_attribute_name_interning (test.test_pickle.PyPicklerTests) ... ok
File "D:\a\1\b\layout-appx-amd64\lib\test\pickletester.py", line 3085 in __getattr__
File "D:\a\1\b\layout-appx-amd64\lib\test\pickletester.py", line 3085 in __getattr__
File "D:\a\1\b\layout-appx-amd64\lib\test\pickletester.py", line 3085 in __getattr__
File "D:\a\1\b\layout-appx-amd64\lib\test\pickletester.py", line 3085 in __getattr__
...
I assume this is due to having more code on the start at the start, and so the recursion limit isn't low enough. But it might also be worth checking this particular case to see whether there is unnecessary data being kept on the stack (e.g. in local C variables).
The crash occurs in both 3.8 and master, but not 3.7.
zooba commentedon May 1, 2020
Turns out the stack reservation was different, which is why it was crashing.
As part of diagnosing it, I added the recursion count to faulthandler's output on Windows, but couldn't see if/where to do it for other platforms - Victor, any suggestions?
zooba commentedon May 1, 2020
Also, it was really test_bad_getattr that was crashing.
[-]test_attribute_name_interning crashes on APPX test[/-][+]test_bad_getattr crashes on APPX test[/+][-]test_attribute_name_interning crashes on APPX test[/-][+]test_bad_getattr crashes on APPX test[/+]vstinner commentedon May 1, 2020
Ah, an old friend. It seems like an issue with the maximum stack size. Here are my notes:
https://pythondev.readthedocs.io/unstable_tests.html#unlimited-recursion
Either reduce Python maximum stack depth, or increase the C stack size.
zooba commentedon May 4, 2020
Yeah, I already got that part. If you check the PR, I added some better diagnostics to faulthandler for this case, but I don't see where I can add it for other platforms?
zooba commentedon May 5, 2020
New changeset ac4bf42 by Steve Dower in branch 'master':
bpo-40458: Increase reserved stack space to prevent overflow crash on Windows (GH-19845)
ac4bf42
zooba commentedon May 5, 2020
Merged without the improved diagnostics. I might add that later if I get time.
Łukasz - this is a fairly trivial crash fix that'd be nice (and safe) to pull into 3.8.3, but not critical. Your call.
miss-islington commentedon May 5, 2020
New changeset a6a116c by Miss Islington (bot) in branch '3.8':
bpo-40458: Increase reserved stack space to prevent overflow crash on Windows (GH-19845)
a6a116c