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test_multiprocessing_fork: test_nested_startmethod() fails randomly. #109706

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vstinner opened this issue Sep 22, 2023 · 0 comments
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test_multiprocessing_fork: test_nested_startmethod() fails randomly. #109706

vstinner opened this issue Sep 22, 2023 · 0 comments
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tests Tests in the Lib/test dir

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vstinner commented Sep 22, 2023 •
edited by bedevere-app bot
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test_nested_startmethod() fails randomly. Since there is no synchronization, putting items in the queue is not really ordered.

I suggest to either accept [1, 2] and [2, 1] in the test, or add some kind of synchronization to ensure that events happen in the expected order. Here I don't think that order matters.

The test was added by PR #108568 of issue gh-108520.

FAIL: test_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/buildbot/buildarea/3.x.cstratak-RHEL7-ppc64le.lto/build/Lib/test/_test_multiprocessing.py", line 5475, in test_nested_startmethod
    self.assertEqual(results, [2, 1])
AssertionError: Lists differ: [1, 2] != [2, 1]

First differing element 0:
1
2

- [1, 2]
+ [2, 1]

build: https://buildbot.python.org/all/#/builders/503/builds/3941

The failure can be reproduced by stressing the test:

$ ./python -m test test_multiprocessing_fork.test_misc -m test_nested_startmethod -v -j50 --forever
(...)
0:00:24 load avg: 20.03 [157/1] test_multiprocessing_fork.test_misc failed (1 failure)
test_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod) ... FAIL

======================================================================
FAIL: test_nested_startmethod (test.test_multiprocessing_fork.test_misc.TestStartMethod.test_nested_startmethod)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/vstinner/python/3.11/Lib/test/_test_multiprocessing.py", line 5399, in test_nested_startmethod
    self.assertEqual(results, [2, 1])
AssertionError: Lists differ: [1, 2] != [2, 1]

First differing element 0:
1
2

- [1, 2]
+ [2, 1]

----------------------------------------------------------------------
Ran 1 test in 2.150s

FAILED (failures=1)
test test_multiprocessing_fork.test_misc failed

Linked PRs
@vstinner vstinner added the tests Tests in the Lib/test dir label Sep 22, 2023
vstinner added a commit to vstinner/cpython that referenced this issue Sep 22, 2023
@vstinner
pythongh-109706: Fix multiprocessing test_nested_startmethod()
85c918b 
Don't check order, queue items can be written in any order.
vstinner added a commit to vstinner/cpython that referenced this issue Sep 22, 2023
@vstinner
pythongh-109706: Fix multiprocessing test_nested_startmethod()
06aa63b 
Don't check order, queue items can be written in any order.
@bedevere-app bedevere-app bot mentioned this issue Sep 22, 2023
Merged
@vstinner vstinner mentioned this issue Sep 22, 2023
Merged
vstinner added a commit that referenced this issue Sep 22, 2023
@vstinner
gh-109706: Fix multiprocessing test_nested_startmethod() (#109707)
b03a791 
Don't check order, queue items can be written in any order.
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Sep 22, 2023
@vstinner @miss-islington
pythongh-109706: Fix multiprocessing test_nested_startmethod() (pytho…
a83132f 
…nGH-109707)

Don't check order, queue items can be written in any order.
(cherry picked from commit b03a791)

Co-authored-by: Victor Stinner <vstinner@python.org>
@bedevere-app bedevere-app bot mentioned this issue Sep 22, 2023
Merged
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Sep 22, 2023
@vstinner @miss-islington
pythongh-109706: Fix multiprocessing test_nested_startmethod() (pytho…
9b81414 
…nGH-109707)

Don't check order, queue items can be written in any order.
(cherry picked from commit b03a791)

Co-authored-by: Victor Stinner <vstinner@python.org>
@bedevere-app bedevere-app bot mentioned this issue Sep 22, 2023
Merged
vstinner added a commit that referenced this issue Sep 22, 2023
@miss-islington @vstinner
[3.11] gh-109706: Fix multiprocessing test_nested_startmethod() (GH-1…
3db2ec2 
…09707) (#109763)

gh-109706: Fix multiprocessing test_nested_startmethod() (GH-109707)

Don't check order, queue items can be written in any order.
(cherry picked from commit b03a791)

Co-authored-by: Victor Stinner <vstinner@python.org>
csm10495 pushed a commit to csm10495/cpython that referenced this issue Sep 28, 2023
@vstinner @csm10495
pythongh-109706: Fix multiprocessing test_nested_startmethod() (pytho…
0066283 
…n#109707)

Don't check order, queue items can be written in any order.
Yhg1s pushed a commit that referenced this issue Oct 2, 2023
@miss-islington @vstinner
[3.12] gh-109706: Fix multiprocessing test_nested_startmethod() (GH-1…
6a6bea3 
…09707) (#109762)

gh-109706: Fix multiprocessing test_nested_startmethod() (GH-109707)

Don't check order, queue items can be written in any order.
(cherry picked from commit b03a791)

Co-authored-by: Victor Stinner <vstinner@python.org>
Glyphack pushed a commit to Glyphack/cpython that referenced this issue Sep 2, 2024
@vstinner @Glyphack
pythongh-109706: Fix multiprocessing test_nested_startmethod() (pytho…
ba451d2 
…n#109707)

Don't check order, queue items can be written in any order.
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