Crash report
What happened?
Hello! Thank you for all your work on CPython. Hopefully this crash report is helpful.
While working on matplotlib/matplotlib#28861, we noticed that our tests were segfaulting, and only on python3.13. Here is a minimal reproduction of that crash. I've also run it with python3.13-dbg and -X dev to hopefully provide more details.
Error Message
python: ../Objects/capsule.c:321: capsule_traverse: Assertion `capsule->traverse_func != NULL' failed.
Minimal Reproducible Example:
$ python3.13 -m venv venv_313
$ source venv_313/bin/activate
$ pip install matplotlib==3.9.2
$ python -X dev test.py
test.py
import gc
from collections import deque
from matplotlib.figure import Figure
from matplotlib.lines import Line2D
from matplotlib.collections import PathCollection
def get_children(parent):
if parent.__class__.__qualname__ == "PyCapsule":
print(f"About to call gc.get_referents on {repr(parent)}")
children = gc.get_referents(parent) # gc.get_referrers does not segfault, but gc.get_referents does
if parent.__class__.__qualname__ == "PyCapsule":
print(f"There are {len(children)} children")
return children
def breadth_first_search(start):
to_visit = deque([start])
explored = set()
try:
gc.disable() # Can repro without this, but it should make behavior more consistent
while len(to_visit) > 0:
parent = to_visit.popleft()
for child in get_children(parent):
if id(child) in explored:
continue
explored.add(id(child))
to_visit.append(child)
finally:
gc.enable()
def find_reference_cycles():
fig = Figure()
ax = fig.add_subplot()
ax.plot([1])
fig.clear()
breadth_first_search(fig)
if __name__ == "__main__":
find_reference_cycles()with python3.13 on Ubuntu 22.04.4
$ python -VV
Python 3.13.0rc2 (main, Sep 9 2024, 22:55:42) [GCC 11.4.0]
$ python -X dev test.py
About to call gc.get_referents on <capsule object "pybind11_function_record_capsule" at 0x7f79954f34d0>
Fatal Python error: Segmentation fault
Current thread 0x00007f79e687f280 (most recent call first):
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 10 in get_children
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 22 in breadth_first_search
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 35 in find_reference_cycles
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 38 in <module>
Extension modules: numpy._core._multiarray_umath, numpy.linalg._umath_linalg, PIL._imaging, kiwisolver._cext (total: 4)
Segmentation fault (core dumped)
with python3.13-dbg on Ubuntu 22.04.4:
$ python -VV
Python 3.13.0rc2 (main, Sep 9 2024, 22:55:42) [GCC 11.4.0]
$ python -X dev test.py
About to call gc.get_referents on <capsule object "pybind11_function_record_capsule" at 0x7f0c31adba80>
python: ../Objects/capsule.c:321: capsule_traverse: Assertion `capsule->traverse_func != NULL' failed.
Fatal Python error: Aborted
Current thread 0x00007f0c82d1a280 (most recent call first):
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 10 in get_children
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 22 in breadth_first_search
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 35 in find_reference_cycles
File "/home/justin/tmp/matplotlib_py313_segfault/test.py", line 38 in <module>
Extension modules: numpy._core._multiarray_umath, numpy.linalg._umath_linalg, PIL._imaging, kiwisolver._cext (total: 4)
Aborted (core dumped)
It does not crash with python3.12 on Ubuntu 22.04.4
$ python -VV
Python 3.12.6 (main, Sep 10 2024, 00:05:17) [GCC 11.4.0]
$ python -X dev test.py
About to call gc.get_referents on <capsule object "pybind11_function_record_capsule" at 0x7f85a852a570>
There are 0 children
[ ... many similar log lines removed ... ]
Side-note:
I tested this on both python3.12 and 3.13, but not the main branch. The Github Issue dropdown doesn't have a 3.13rc2 option for me to check.
CPython versions tested on:
3.12
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.13.0rc2 (main, Sep 9 2024, 22:55:42) [GCC 11.4.0]
Linked PRs
Crash report
What happened?
Hello! Thank you for all your work on CPython. Hopefully this crash report is helpful.
While working on matplotlib/matplotlib#28861, we noticed that our tests were segfaulting, and only on python3.13. Here is a minimal reproduction of that crash. I've also run it with python3.13-dbg and
-X devto hopefully provide more details.Error Message
Minimal Reproducible Example:
test.py
with python3.13 on Ubuntu 22.04.4
with python3.13-dbg on Ubuntu 22.04.4:
It does not crash with python3.12 on Ubuntu 22.04.4
Side-note:
I tested this on both python3.12 and 3.13, but not the main branch. The Github Issue dropdown doesn't have a 3.13rc2 option for me to check.
CPython versions tested on:
3.12
Operating systems tested on:
Linux
Output from running 'python -VV' on the command line:
Python 3.13.0rc2 (main, Sep 9 2024, 22:55:42) [GCC 11.4.0]
Linked PRs
gc.get_referentson an untracked capsule object #124559gc.get_referentson an untracked capsule object (GH-124559) #124588