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test_dtrace fails on s390x Fedora buildbots #158294
Description
Bug report
Bug description:
Saw in #157045 (specifically 5693c85). Failing builds seem to be only on Fedora s390x. For example:
- https://buildbot.python.org/#/builders/1634/builds/579
- https://buildbot.python.org/#/builders/1666/builds/579
- https://buildbot.python.org/#/builders/1643/builds/580
- https://buildbot.python.org/#/builders/1640/builds/582
- https://buildbot.python.org/#/builders/1652/builds/583
- https://buildbot.python.org/#/builders/1630/builds/674
Here's the traceback:
======================================================================
FAIL: test_function_entry_return (test.test_dtrace.SystemTapNormalTests.test_function_entry_return)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/var/lib/buildbot/worker/cstratak-fedora-stable-s390x/pull_request.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_dtrace.py", line 466, in test_function_entry_return
self.run_case("call_stack")
~~~~~~~~~~~~~^^^^^^^^^^^^^^
File "/var/lib/buildbot/worker/cstratak-fedora-stable-s390x/pull_request.cstratak-fedora-stable-s390x.refleak/build/Lib/test/test_dtrace.py", line 463, in run_case
self.assertEqual(actual_output, expected_output)
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AssertionError: 'func[21 chars]k.py:function_1:1\nfunction__entry:call_stack.[642 chars]5:21' != 'func[21 chars]k.py:start:23\nfunction__entry:call_stack.py:f[723 chars]t:28'I'm unsure whether this is a known issue already, but I couldn't find any existing reports.
CPython versions tested on:
CPython main branch
Operating systems tested on:
No response
Activity
hugovk commentedon Sep 28, 2026
cc @stratakis @vstinner
stratakis commentedon Sep 28, 2026
This is an issue with the latest systemtap 5.6, the s390x got the update. From its changelog:
call_stack.stp defines handlers to be run in specific order but Systemtap makes no guarantees about that and the latest version exposed the issue. Combining the logic there into one handler should fix it.
gh-158294: Avoid relying on SystemTap probe handler ordering (#158346)
[3.15] gh-158294: Avoid relying on SystemTap probe handler ordering (G…
encukou commentedon Sep 29, 2026
Thank you for the fix!
The redness is down to one slow refleaks bot; time to close.