ModuleNotFoundError: No module named '_posixshmem' when using multiprocessing #6038
Description
Summary
When attempting to run a Python script that utilizes the multiprocessing module, RustPython fails with a ModuleNotFoundError. The interpreter cannot find the _posixshmem module, which seems to be a dependency for the multiprocessing library's resource tracker on POSIX systems.
Expected
The script should execute without raising a ModuleNotFoundError, allowing the multiprocessing.Process to start and run the target function.
Actual
--- Testing: (simple_recursive_fibonacci) ---
Traceback (most recent call last):
File "src/main.py", line 149, in <module>
name, n, num_digits = performance_tester(func)
File "src/main.py", line 95, in performance_tester
median_runtime: float = time_execution(n)
File "src/main.py", line 75, in time_execution
process.start()
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/process.py", line 121, in start
self._popen = self._Popen(self)
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/context.py", line 224, in _Popen
return _default_context.get_context().Process._Popen(process_obj)
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/context.py", line 289, in _Popen
return Popen(process_obj)
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/popen_spawn_posix.py", line 32, in __init__
super().__init__(process_obj)
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/popen_fork.py", line 20, in __init__
self._launch(process_obj)
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/popen_spawn_posix.py", line 39, in _launch
from . import resource_tracker
File "/Users/wallacy/.cargo/git/checkouts/rustpython-63090cdce5e18442/4079776/pylib/Lib/multiprocessing/resource_tracker.py", line 42, in <module>
import _posixshmem
ModuleNotFoundError: No module named '_posixshmem'
System Information
- OS: macOS Monterey 12.7.6
- RustPython Version:
Python 3.13.0alpha (heads/master:4079776c3, Jul 25 2025, 12:42:22)
[RustPython 0.4.0 with rustc 1.88.0 (6b00bc388 2025-06-23)]
Code to Reproduce
Just download the file and run it.
rustpython main.py
Update - 2025-07-25 21:39 UTC
I just tested it in Docker with the Arch Linux image and it worked perfectly. I used the following commands:
docker run -it --rm archlinux:base-devel-20250720.0.386825 bash
pacman -Syu git
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh
source $HOME/.cargo/env
cargo install --git https://github.com/RustPython/RustPython rustpython
git clone https://github.com/WallPasq/fibonacci.git
rustpython fibonacci/src/main.pyHowever, it still doesn't work on macOS, so I don't think the issue is hardware-related.