python / python/cpython

Segfault in `test_sampling_profiler`

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tests topic-profiling type-crash
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Python
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Description

Crash report

What happened?

A recent Buildbot run (AMD64 Debian root) saw a segfault in test_sampling_profiler: https://buildbot.python.org/#/builders/345/builds/12988

test_sampling_all_threads (test.test_profiling.test_sampling_profiler.test_integration.TestSampleProfilerIntegration.test_sampling_all_threads) ... Fatal Python error: Segmentation fault

Current thread 0x00007f85531fa740 [python] (most recent call first):
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/profiling/sampling/sample.py", line 75 in sample
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/profiling/sampling/sample.py", line 350 in sample
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/test_profiling/test_sampling_profiler/test_integration.py", line 521 in test_sampling_all_threads
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 613 in _callTestMethod
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 667 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/case.py", line 723 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 122 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/suite.py", line 84 in __call__
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/unittest/runner.py", line 257 in run
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 84 in _run_suite
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 42 in run_unittest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 162 in test_func
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 118 in regrtest_runner
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 165 in _load_run_test
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 210 in _runtest_env_changed_exc
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 319 in _runtest
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/single.py", line 348 in run_single_test
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 99 in worker_process
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 134 in main
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/test/libregrtest/worker.py", line 138 in <module>
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 87 in _run_code
  File "/root/buildarea/3.x.angelico-debian-amd64/build/Lib/runpy.py", line 196 in _run_module_as_main

Current thread's C stack trace (most recent call first):
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _Py_DumpStack+0x33 [0x563947ed22d4]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x3285b2 [0x563947eea5b2]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x328caa [0x563947eeacaa]
  Binary file "/lib/x86_64-linux-gnu/libc.so.6", at +0x3bfd0 [0x7f8553238fd0]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x5795 [0x563947e2bc9a]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f1c1 [0x563947cf11c1]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f326 [0x563947cf1326]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12da86 [0x563947cefa86]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12dd76 [0x563947cefd76]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at PyObject_Call+0x20 [0x563947cefdae]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x60a2 [0x563947e2c5a7]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12d7d3 [0x563947cef7d3]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12d99d [0x563947cef99d]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x1c26af [0x563947d846af]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x1c278d [0x563947d8478d]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyObject_MakeTpCall+0xce [0x563947cee47c]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12c6af [0x563947cee6af]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at PyObject_Vectorcall+0x23 [0x563947cee6fd]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _Py_VectorCall_StackRefSteal+0x86 [0x563947e237d2]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyEval_EvalFrameDefault+0x90b2 [0x563947e2f5b7]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280c92 [0x563947e42c92]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x280e44 [0x563947e42e44]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at _PyFunction_Vectorcall+0x54 [0x563947cee2da]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f1c1 [0x563947cf11c1]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12f326 [0x563947cf1326]
  Binary file "/root/buildarea/3.x.angelico-debian-amd64/build/python", at +0x12da86 [0x563947cefa86]
  <truncated rest of calls>

A similar crash happened earlier in the run in test_sampling_with_collapsed_export.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Output from running 'python -VV' on the command line:

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with Lib/profiling/sampling/sample.py around the reported lines 75 and 350, then inspect Lib/test/test_profiling/test_sampling_profiler/test_integration.py around test_sampling_all_threads and test_sampling_with_collapsed_export. Reproduce the failing sampling-profiler tests on Linux and trace the segfault. Done means the affected tests complete without a segmentation fault and the regression is covered by the relevant test suite.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
performance, testing
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
30/100

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