Not sure why this is suddenly happening now and only on the NumPy nightly wheels, but it migbt be relevant that this warning was seen as a bug by upstream and they made the resource_tracker reentrant-safe: https://github.com/python/cpython/issues/131788
This is merged in `main`, backported to 3.13 and released in 3.13.7, but has not yet been backported to 3.14 because that branch is in the RC freeze. I happened to know about this because it caused some breakage in joblib, but that’s been fixed for a month or so. On Mon, Sep 22, 2025 at 8:05 PM Andrew Nelson via NumPy-Discussion < [email protected]> wrote: > Hi all, > in the last few weeks have there been any PRs that have touched objects > that are followed by the Python ResourceTracker. I'm talking about things > like Locks, semaphores, mutexes, etc? > > I'm seeing some weird behaviour in scipy CI where a test ( > https://github.com/scipy/scipy/blob/main/scipy/optimize/tests/test_optimize.py#L3442) > that uses an object that wraps `multiprocessing.Pool` has started giving > test fails. A typical log ( > https://github.com/scipy/scipy/actions/runs/17925659616/job/50971069339#step:12:1229) > has text like: > > "multiprocessing.resource_tracker.ReentrantCallError: Reentrant call into > the multiprocessing resource tracker" > and > "UserWarning: ResourceTracker called reentrantly for resource cleanup, > which is unsupported. The semaphore object '/mp-380ciby1' might leak." > > In my investigations (https://github.com/andyfaff/scipy/pull/83) it only > seems to happen for cp312 and the numpy nightly wheel. It doesn't seem to > trigger for cp312+np2.3.3 or for cp311. > > Given that it only seems to happen with the numpy nightly wheel I'm > wondering if it's therefore a numpy issue. As far as I can tell it's > started happening in the last five days or so. > > > -- > _____________________________________ > Dr. Andrew Nelson > > > _____________________________________ > _______________________________________________ > NumPy-Discussion mailing list -- [email protected] > To unsubscribe send an email to [email protected] > https://mail.python.org/mailman3//lists/numpy-discussion.python.org > Member address: [email protected] >
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