Regression in Python 3.14.0a7. #133352
Description
Crash report
What happened?
I noticed a regression in Python 3.14.0 alpha 7. One of tests from Django test suite crashes test_runner.test_parallel.ParallelTestSuiteTest.test_handle_add_error_before_first_test:
$ ./runtests.py test_runner.test_parallel.ParallelTestSuiteTest.test_handle_add_error_before_first_test
Testing against Django installed in '/django/django'
Found 1 test(s).
System check identified no issues (0 silenced).
Fatal Python error: Segmentation fault
Current thread 0x00007858cbcc2b80 [python] (most recent call first):
File "/django/django/test/runner.py", line 185 in _confirm_picklable
File "/django/django/test/runner.py", line 215 in check_picklable
File "/django/django/test/runner.py", line 294 in addError
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 246 in _addClassOrModuleLevelException
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 236 in _createClassOrModuleLevelException
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 176 in _handleClassSetUp
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 114 in run
File "/django/tests/test_runner/test_parallel.py", line 225 in test_handle_add_error_before_first_test
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/case.py", line 615 in _callTestMethod
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/case.py", line 669 in run
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/case.py", line 725 in __call__
File "/django/django/test/testcases.py", line 357 in _setup_and_call
File "/django/django/test/testcases.py", line 302 in __call__
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 122 in run
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/suite.py", line 84 in __call__
File ".pyenv/versions/3.14-dev/lib/python3.14/unittest/runner.py", line 259 in run
File "/django/django/test/runner.py", line 1020 in run_suite
File "/django/django/test/runner.py", line 1093 in run_tests
File "/django/tests/./runtests.py", line 427 in django_tests
File "/django/tests/./runtests.py", line 788 in <module>
Current thread's C stack trace (most recent call first):
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _Py_DumpStack+0x45 [0x7858cb8e3145]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x2f85d4 [0x7858cb8f85d4]
Binary file "/lib/x86_64-linux-gnu/libc.so.6", at +0x42520 [0x7858cb242520]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at PyObject_GC_UnTrack+0x19 [0x7858cb887269]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x2e08a3 [0x7858cb8e08a3]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x10cb15 [0x7858cb70cb15]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x10d235 [0x7858cb70d235]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x18e862 [0x7858cb78e862]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyEval_EvalFrameDefault+0x8ec9 [0x7858cb699059]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x254fba [0x7858cb854fba]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfea03 [0x7858cb6fea03]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyEval_EvalFrameDefault+0x1e48 [0x7858cb691fd8]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x254fba [0x7858cb854fba]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfc8ea [0x7858cb6fc8ea]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfcb40 [0x7858cb6fcb40]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x19d144 [0x7858cb79d144]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyObject_MakeTpCall+0x86 [0x7858cb6fa506]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyEval_EvalFrameDefault+0x1c1e [0x7858cb691dae]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x254fba [0x7858cb854fba]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfea03 [0x7858cb6fea03]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyEval_EvalFrameDefault+0x1e48 [0x7858cb691fd8]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x254fba [0x7858cb854fba]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfc8ea [0x7858cb6fc8ea]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0xfcb40 [0x7858cb6fcb40]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x19d144 [0x7858cb79d144]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyObject_MakeTpCall+0x86 [0x7858cb6fa506]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at _PyEval_EvalFrameDefault+0x1c1e [0x7858cb691dae]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at PyEval_EvalCode+0x1dd [0x7858cb854ced]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x2c57ad [0x7858cb8c57ad]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x2c7996 [0x7858cb8c7996]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at +0x2c7f3f [0x7858cb8c7f3f]
Binary file ".pyenv/versions/3.14-dev/lib/libpython3.14.so.1.0", at Py_RunMain+0x996 [0x7858cb8f64e6]
<truncated rest of calls>
Extension modules: pywatchman.bser, markupsafe._speedups (total: 2)
Segmentation fault (core dumped)It also crashes on the current main branch of cpython (reproduced at 1550c30 compiled with debug):
$ runtests.py test_runner.test_parallel.ParallelTestSuiteTest.test_handle_add_error_before_first_test
Testing against Django installed in '/django/django'
Found 1 test(s).
System check identified no issues (0 silenced).
./Include/refcount.h:526: _Py_NegativeRefcount: Assertion failed: object has negative ref count
<object at 0x7fc6598b3930 is freed>
Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: initialized
Traceback (most recent call last):
File "/cpython/Lib/unittest/suite.py", line 166, in _handleClassSetUp
setUpClass()
~~~~~~~~~~^^
File "/django/tests/test_runner/test_parallel.py", line 74, in setUpClass
raise ValueError("woops")
ValueError: woops
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/django/tests/.test-python-dev/lib/python3.14/site-packages/tblib/pickling_support.py", line 30, in unpickle_exception
inst.__traceback__ = tb
^^^^^^^^^^^^^^^^^^
TypeError: __traceback__ must be a traceback or None
Extension modules: pywatchman.bser, markupsafe._speedups (total: 2)
Aborted (core dumped)I bisected this regression to the 053c285. Previously it passed with an assertion warning
./runtests.py test_runner.test_parallel.ParallelTestSuiteTest.test_handle_add_error_before_first_test
Testing against Django installed in '/workspace/repo/django/django'
Found 1 test(s).
System check identified no issues (0 silenced).
.
----------------------------------------------------------------------
Ran 1 test in 0.002s
OK
Objects/typeobject.c:6226: _Py_NegativeRefcount: Assertion failed: object has negative ref count
Enable tracemalloc to get the memory block allocation traceback
object address : 0x7cd1aa2aa1c0
object refcount : 4294967295
object type : 0x63d9c0393140
object type name: type
object repr : <class 'bserobj_tuple'>
Fatal Python error: _PyObject_AssertFailed: _PyObject_AssertFailed
Python runtime state: finalizing (tstate=0x000063d9c0404558)
Current thread 0x00007cd1ab58b740 (most recent call first):
<no Python frame>
Aborted (core dumped)CPython versions tested on:
3.14
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.14.0a7+ (heads/main:6a9bfee4fa1, Apr 25 2025, 10:31:59) [GCC 11.4.0]