Crash when using _Py_DumpTracebackThreads #128400
Description
Crash report
What happened?
# triggering program # based on test.test_faulthandler.FaultHandlerTests.test_dump_traceback_threads import faulthandler from threading import Thread, Event class Waiter(Thread): def __init__(self): Thread.__init__(self) self.running = Event() self.stop = Event() def run(self): self.running.set() self.stop.wait() def main(): for i in range(100): waiter = Waiter() waiter.start() waiter.running.wait() faulthandler.dump_traceback(all_threads=True) waiter.stop.set() waiter.join() if __name__ == '__main__': main()This will case the interpreter to segfault if built with --disable-gil --with-pydebug. I've bisected it to this commit:
Using gdb:
Thread 1 "python" received signal SIGSEGV, Segmentation fault. _PyFrame_GetCode (f=f@entry=0x7ffff7fb32d8) at ./Include/internal/pycore_frame.h:83 83 assert(PyCode_Check(executable)); (gdb) p executable $7 = 0x0 (gdb) bt #0 _PyFrame_GetCode (f=f@entry=0x7ffff7fb32d8) at ./Include/internal/pycore_frame.h:83 #1 PyUnstable_InterpreterFrame_GetLine (frame=frame@entry=0x7ffff7fb32d8) at Python/frame.c:149 #2 0x000055555590e9eb in dump_frame (fd=2, frame=0x7ffff7fb32d8) at Python/traceback.c:905 #3 dump_traceback (fd=fd@entry=2, tstate=tstate@entry=0x555555cef140, write_header=write_header@entry=0) at Python/traceback.c:974 #4 0x000055555590ed1c in _Py_DumpTracebackThreads (fd=2, interp=<optimized out>, interp@entry=0x0, current_tstate=0x555555c5dea8 <_PyRuntime+359528>) at Python/traceback.c:1090 #5 0x0000555555924489 in faulthandler_dump_traceback_py (self=<optimized out>, args=<optimized out>, kwargs=<optimized out>) at ./Modules/faulthandler.c:240 #6 0x00005555556feae1 in cfunction_call (func=func@entry=<built-in method dump_traceback of module object at remote 0x20000778900>, args=args@entry=(), kwargs=kwargs@entry={'all_threads': True}) [...] CPython versions tested on:
CPython main branch
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.14.0a0 experimental free-threading build (bisect/bad:b2afe2aae48, Jan 1 2025, 17:09:16) [Clang 19.1.6 (++20241217105838+657e03f8625c-1exp120241217105944.74)]
Linked PRs
- gh-128400: Stop-the-world when manually calling
faulthandler#128422 - [3.13] gh-128400: Stop-the-world when manually calling
faulthandler(GH-128422) #128423 - gh-128400: Only show the current thread in
faulthandlerif the GIL is disabled #128425 - gh-128400: Only show the current thread in
Py_FatalErroron the free-threaded build #128758