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GH-140815: Acquire GIL or stop the world when calling _Py_DumpTracebackThreads from faulthandler_thread #140895

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GH-140815: Acquire GIL or stop the world when calling _Py_DumpTracebackThreads from faulthandler_thread #140895

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2821264
Acquire GIL or stop the world when calling _Py_DumpTracebackThreads f…
sergey-miryanov Nov 1, 2025
1d7eeb5
Make CI happy
sergey-miryanov Nov 1, 2025
4491118
Don't skip current tstate + update tests
sergey-miryanov Nov 2, 2025
6d2c945
Replace use PyGILState_Ensure with PyThreadState_New + _PyThreadState…
sergey-miryanov Nov 2, 2025
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Don't skip current tstate + update tests
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@sergey-miryanov
sergey-miryanov committed Nov 2, 2025
commit 4491118b1168772a4dddb0d0b60c6adb9c43b35a
6 changes: 1 addition & 5 deletions Include/internal/pycore_traceback.h
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Expand Up @@ -56,16 +56,12 @@ extern void _Py_DumpTraceback(
It is better to pass NULL to interp and current_tstate, the function tries
different options to retrieve this information.

If skip_current_tstate is 1 then first tstate (current_tstate) will be skiped.
This flag used in faulthandler_thread to skip self.

This function is signal safe. */

extern const char* _Py_DumpTracebackThreads(
int fd,
PyInterpreterState *interp,
PyThreadState *current_tstate,
int skip_current_tstate);
PyThreadState *current_tstate);

/* Write a Unicode object into the file descriptor fd. Encode the string to
ASCII using the backslashreplace error handler.
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3 changes: 3 additions & 0 deletions Lib/test/test_faulthandler.py
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Expand Up @@ -31,6 +31,7 @@
THREAD_HEADER = fr'{THREAD_ID} \(most recent call first\):'
CURRENT_THREAD_ID = fr'Current thread 0x[0-9a-f]+{THREAD_NAME}'
CURRENT_THREAD_HEADER = fr'{CURRENT_THREAD_ID} \(most recent call first\):'
THREAD_NO_PYTHON_FRAME = ' <no Python frame>'


def expected_traceback(lineno1, lineno2, header, min_count=1):
Expand Down Expand Up @@ -676,6 +677,8 @@ def func(timeout, repeat, cancel, file, loops):
if repeat:
count *= 2
header = (fr'Timeout \({timeout_str}\)!\n'
fr'{CURRENT_THREAD_HEADER}\n'
fr'{THREAD_NO_PYTHON_FRAME}\n\n'
fr'{THREAD_HEADER}\n')
regex = expected_traceback(17, 26, header, min_count=count)
self.assertRegex(trace, regex)
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4 changes: 2 additions & 2 deletions Modules/faulthandler.c
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Expand Up @@ -205,7 +205,7 @@ faulthandler_dump_traceback(int fd, int all_threads,
PyThreadState *tstate = PyGILState_GetThisThreadState();

if (all_threads == 1) {
(void)_Py_DumpTracebackThreads(fd, NULL, tstate, 0);
(void)_Py_DumpTracebackThreads(fd, NULL, tstate);
}
else {
if (all_threads == FT_IGNORE_ALL_THREADS) {
Expand Down Expand Up @@ -273,7 +273,7 @@ faulthandler_dump_traceback_py_impl(PyObject *module, PyObject *file,
/* gh-128400: Accessing other thread states while they're running
* isn't safe if those threads are running. */
_PyEval_StopTheWorld(interp);
errmsg = _Py_DumpTracebackThreads(fd, NULL, tstate, 0);
errmsg = _Py_DumpTracebackThreads(fd, NULL, tstate);
_PyEval_StartTheWorld(interp);
if (errmsg != NULL) {
PyErr_SetString(PyExc_RuntimeError, errmsg);
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2 changes: 1 addition & 1 deletion Python/pylifecycle.c
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Expand Up @@ -3139,7 +3139,7 @@ _Py_FatalError_DumpTracebacks(int fd, PyInterpreterState *interp,

/* display the current Python stack */
#ifndef Py_GIL_DISABLED
_Py_DumpTracebackThreads(fd, interp, tstate, 0);
_Py_DumpTracebackThreads(fd, interp, tstate);
#else
_Py_DumpTraceback(fd, tstate);
#endif
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9 changes: 1 addition & 8 deletions Python/traceback.c
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Expand Up @@ -1239,8 +1239,7 @@ write_thread_id(int fd, PyThreadState *tstate, int is_current)
handlers if signals were received. */
const char*
_Py_DumpTracebackThreads(int fd, PyInterpreterState *interp,
PyThreadState *current_tstate,
int skip_current_tstate)
PyThreadState *current_tstate)
{
if (current_tstate == NULL) {
/* _Py_DumpTracebackThreads() is called from signal handlers by
Expand Down Expand Up @@ -1290,12 +1289,6 @@ _Py_DumpTracebackThreads(int fd, PyInterpreterState *interp,
_Py_BEGIN_SUPPRESS_IPH
do
{
if (skip_current_tstate && current_tstate == tstate) {
tstate = PyThreadState_Next(tstate);
skip_current_tstate = 0;
continue;
}

if (nthreads != 0)
PUTS(fd, "\n");
if (nthreads >= MAX_NTHREADS) {
Expand Down