CPython 3.11.11 from uv fails on multiprocessing.Queue().qsize() (aarch64) #977
Description
Summary
When creating a venv with uv and Python 3.11.11 on linux aarch64, calling multiprocessing.Queue().qsize() raises NotImplementedError. The same code works with uv-managed 3.12.12 and system 3.10.12.
Environment
- OS: Linux (aarch64)
- uv: 0.10.0
- Python (uv-managed):
- 3.11.11 →
NotImplementedError - 3.12.12 → works
- 3.12.14 → works
- 3.11.11 →
- Python (system):
- 3.10.12 → works
Reproduction (sanitized)
user@host:~$ uv venv --python=3.11.11
Using CPython 3.11.11
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate
user@host:~$ source .venv/bin/activate
(venv) user@host:~$ python - <<'PY'
from multiprocessing import Queue
q = Queue()
q.put(1)
q.put(2)
print('uv venv qsize:', q.qsize())
PY
Traceback (most recent call last):
File "<stdin>", line 5, in <module>
File "/home/<redacted>/.local/share/uv/python/cpython-3.11.11-linux-aarch64-gnu/lib/python3.11/multiprocessing/queues.py", line 126, in qsize
return self._maxsize - self._sem._semlock._get_value()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
NotImplementedErrorExpected
qsize() returns 2 (same as 3.12.12 and system 3.10.12).
Comparison
uv Python 3.12.12 (works)
user@host:~$ uv venv --python=3.12
Using CPython 3.12.12
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate
user@host:~$ source .venv/bin/activate
(venv) user@host:~$ python - <<'PY'
from multiprocessing import Queue
q = Queue()
q.put(1)
q.put(2)
print('uv venv qsize:', q.qsize())
PY
uv venv qsize: 2system Python 3.10.12 (works)
user@host:~$ uv venv --python=3.10
Using CPython 3.10.12 interpreter at: /usr/bin/python3.10
Creating virtual environment at: .venv
Activate with: source .venv/bin/activate
user@host:~$ source .venv/bin/activate
(venv) user@host:~$ python - <<'PY'
from multiprocessing import Queue
q = Queue()
q.put(1)
q.put(2)
print('uv venv qsize:', q.qsize())
PY
uv venv qsize: 2Notes
This looks specific to the uv-provided CPython 3.11.11 build on aarch64.