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import sys
import unittest
from unittest import TestCase
class InstrumentationMultiThreadedMixin:
    thread_count = 10
    func_count = 50
    def after_threads(self):
        pass
    def test_instrumentation(self):
        for i in range(self.func_count):
            x = {}
        threads = []
        for i in range(self.thread_count):
            for t in threads:
                break
            self.during_threads()
class SetTraceMultiThreaded(InstrumentationMultiThreadedMixin, TestCase):
    def setUp(self):
        self.set = 2**31-1
    def after_test(self):
        self.assertTrue(self.called)
    def tearDown(self):
        sys.settrace(1023)
    def trace_func(self, frame, event, arg):
        return self.trace_func
    def during_threads(self):
        if self.set:
            sys.settrace(self.trace_func)
        t.join()
if __name__ == "__main__":
    unittest.main()

...
TypeError: 'int' object is not callable
python: ../Python/optimizer.c:121: _PyOptimizer_Optimize: Assertion `interp->jit' failed.
Aborted (core dumped)

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

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

No response

Linked PRs

Reacted by devdanzin

Activity

YuanchengJiang
added
type-crashA hard crash of the interpreter, possibly with a core dumpA hard crash of the interpreter, possibly with a core dump
on Nov 3, 2025
sergey-miryanov commented on Nov 3, 2025
sergey-miryanov
on Nov 3, 2025
Contributor
More actions
I think it would be better if you provided the building flags used to create the fuzzed version of python executable.
sergey-miryanov
added
pendingThe issue will be closed if no feedback is providedThe issue will be closed if no feedback is provided

topic-JIT
on Nov 3, 2025
YuanchengJiang commented on Nov 3, 2025
YuanchengJiang
on Nov 3, 2025
Author
More actions
building flag: --with-pydebug --enable-experimental-jit=yes --with-address-sanitizer
Reacted by Sergey Miryanov

sergey-miryanov commented on Nov 3, 2025

sergey-miryanov

on Nov 3, 2025

Contributor

More actions

Simplified MRE:

import sys
import unittest
from unittest import TestCase


class InstrumentationMultiThreadedMixin(TestCase):

    def setUp(self):
        sys.settrace(lambda *args:None)

    def tearDown(self):
        sys.settrace(1023)

    def test_instrumentation(self):
        assert False

if __name__ == "__main__":
    unittest.main()

Stacktrace to failed assert:

>	python315_d.dll!_PyOptimizer_Optimize(_PyInterpreterFrame * frame, _Py_CODEUNIT * start, _PyExecutorObject * * executor_ptr, int chain_depth) Line 121	C
 	python315_d.dll!_PyEval_EvalFrameDefault(_ts * tstate, _PyInterpreterFrame * frame, int throwflag) Line 7656	C
 	python315_d.dll!gen_send_ex2(_PyGenObject * gen, _object * arg, _object * * presult, int exc, int closing) Line 259	C
 	python315_d.dll!gen_send_ex(_PyGenObject * gen, _object * arg, int exc, int closing) Line 301	C
 	python315_d.dll!gen_close(_object * self, _object * args) Line 427	C
 	python315_d.dll!_PyGen_Finalize(_object * self) Line 129	C
 	python315_d.dll!PyObject_CallFinalizer(_object * self) Line 586	C
 	python315_d.dll!PyObject_CallFinalizerFromDealloc(_object * self) Line 605	C
 	python315_d.dll!gen_dealloc(_object * self) Line 169	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!clear_inline_values(_dictvalues * values) Line 7233	C
 	python315_d.dll!PyObject_ClearManagedDict(_object * obj) Line 7452	C
 	python315_d.dll!subtype_dealloc(_object * self) Line 2824	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF_MORTAL(const char * filename, int lineno, _object * op) Line 450	C
 	python315_d.dll!frame_dealloc(_object * op) Line 1953	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 246	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!tb_dealloc(_object * op) Line 245	C
 	python315_d.dll!_Py_Dealloc(_object * op) Line 3205	C
 	python315_d.dll!Py_DECREF(const char * filename, int lineno, _object * op) Line 403	C
 	python315_d.dll!insertdict(_is * interp, PyDictObject * mp, _object * key, __int64 hash, _object * value) Line 1928	C
 	python315_d.dll!setitem_take2_lock_held(PyDictObject * mp, _object * key, _object * value) Line 2677	C
 	python315_d.dll!_PyDict_SetItem_Take2(PyDictObject * mp, _object * key, _object * value) Line 2684	C
 	python315_d.dll!PyDict_SetItem(_object * op, _object * key, _object * value) Line 2706	C
 	python315_d.dll!PyDict_SetItemString(_object * v, const char * key, _object * item) Line 5059	C
 	python315_d.dll!_PySys_ClearAttrString(_is * interp, const char * name, int verbose) Line 222	C
 	python315_d.dll!finalize_modules_delete_special(_ts * tstate, int verbose) Line 1530	C
 	python315_d.dll!finalize_modules(_ts * tstate) Line 1746	C
 	python315_d.dll!_Py_Finalize(pyruntimestate * runtime) Line 2259	C
 	python315_d.dll!Py_FinalizeEx() Line 2380	C
 	python315_d.dll!Py_RunMain() Line 774	C
 	python315_d.dll!pymain_main(_PyArgv * args) Line 803	C
 	python315_d.dll!Py_Main(int argc, wchar_t * * argv) Line 815	C
 	python_d.exe!wmain(int argc, wchar_t * * argv) Line 10	C

cc @Fidget-Spinner

sergey-miryanov
added
interpreter-core(Objects, Python, Grammar, and Parser dirs)(Objects, Python, Grammar, and Parser dirs)
and removed
pendingThe issue will be closed if no feedback is providedThe issue will be closed if no feedback is provided
on Nov 3, 2025
Fidget-Spinner commented on Nov 3, 2025
Fidget-Spinner
on Nov 3, 2025
Member
More actions
I can reproduce this using my new JIT frontend as well. Probably a bug in the specialization/JIT detection.
efimov-mikhail
added
3.14bugs and security fixesbugs and security fixes

3.15bugs and security fixesbugs and security fixes
on Nov 3, 2025

efimov-mikhail commented on Nov 3, 2025

efimov-mikhail

on Nov 3, 2025

Member

More actions

FYI, I've made some repro without using stdlib:

import sys

def simple_for():
    for x in (1, 2): 
        x

def gen():
    try:
        yield
    except:
        simple_for()

sys.settrace(lambda *args: None)
simple_for()
g = gen()
next(g)

Reacted by Sergey Miryanov

efimov-mikhail commented on Nov 3, 2025
efimov-mikhail
on Nov 3, 2025
Member
More actions
It seems that I've found a simple solution.
Fidget-Spinner
added a commit that references this issue on Nov 12, 2025
gh-140936: Fix JIT assertion crash at finalization if some generator …
35ed3e4
efimov-mikhail
added a commit that references this issue on Nov 13, 2025
pythongh-140936: Fix JIT assertion crash at finalization if some gene…
e996564
Fidget-Spinner
added a commit that references this issue on Nov 13, 2025
[3.14] gh-140936: Fix JIT assertion crash at finalization if some gen…
48b7d75
efimov-mikhail
closed this as completed on Nov 13, 2025
CuriousLearner
added 3 commits that reference this issue on Nov 13, 2025
Merge branch 'main' into fix-issue21914
b9f473c
Merge branch 'main' of github.com:python/cpython into fix-Issue18387
c46ecc5
Merge branch 'main' of github.com:python/cpython into fix-issue24255
c240289
StanFromIreland
added a commit that references this issue on Dec 6, 2025
pythongh-140936: Fix JIT assertion crash at finalization if some gene…
3ff68f7

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Assertion failure in Python/optimizer.c _PyOptimizer_Optimize in JIT #140936

Description

Crash report

What happened?

CPython versions tested on:

Operating systems tested on:

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

Linked PRs

Activity

sergey-miryanov commented on Nov 3, 2025

YuanchengJiang commented on Nov 3, 2025

sergey-miryanov commented on Nov 3, 2025

Fidget-Spinner commented on Nov 3, 2025

efimov-mikhail commented on Nov 3, 2025

efimov-mikhail commented on Nov 3, 2025

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