Bug 2480167

python-joblib fails to build with Python 3.15.0b1.

There's quite a few test failures which seem to boil down to the variations of:

_______ test_multithreaded_parallel_termination_resource_tracker_silent ________

    @with_numpy
    @with_multiprocessing
    def test_multithreaded_parallel_termination_resource_tracker_silent():
        # test that concurrent termination attempts of a same executor does not
        # emit any spurious error from the resource_tracker. We test various
        # situations making 0, 1 or both parallel call sending a task that will
        # make the worker (and thus the whole Parallel call) error out.
        cmd = """if 1:
            import os
            import numpy as np
            from joblib import Parallel, delayed
            from joblib.externals.loky.backend import resource_tracker
            from concurrent.futures import ThreadPoolExecutor, wait
    
            resource_tracker.VERBOSE = 0
    
            array = np.arange(int(1e2))
    
            temp_dirs_thread_1 = set()
            temp_dirs_thread_2 = set()
    
    
            def raise_error(array):
                raise ValueError
    
    
            def parallel_get_filename(array, temp_dirs):
                with Parallel(backend="loky", n_jobs=2, max_nbytes=10) as p:
                    for i in range(10):
                        [filename] = p(
                            delayed(getattr)(array, "filename") for _ in range(1)
                        )
                        temp_dirs.add(os.path.dirname(filename))
    
    
            def parallel_raise(array, temp_dirs):
                with Parallel(backend="loky", n_jobs=2, max_nbytes=10) as p:
                    for i in range(10):
                        [filename] = p(
                            delayed(raise_error)(array) for _ in range(1)
                        )
                        temp_dirs.add(os.path.dirname(filename))
    
    
            executor = ThreadPoolExecutor(max_workers=2)
    
            # both function calls will use the same loky executor, but with a
            # different Parallel object.
            future_1 = executor.submit({f1}, array, temp_dirs_thread_1)
            future_2 = executor.submit({f2}, array, temp_dirs_thread_2)
    
            # Wait for both threads to terminate their backend
            wait([future_1, future_2])
    
            future_1.result()
            future_2.result()
        """
        functions_and_returncodes = [
            ("parallel_get_filename", "parallel_get_filename", 0),
            ("parallel_get_filename", "parallel_raise", 1),
            ("parallel_raise", "parallel_raise", 1),
        ]
    
        for f1, f2, returncode in functions_and_returncodes:
            p = subprocess.Popen(
                [sys.executable, "-c", cmd.format(f1=f1, f2=f2)],
                stderr=subprocess.PIPE,
                stdout=subprocess.PIPE,
            )
            p.wait()
            _, err = p.communicate()
            assert p.returncode == returncode, err.decode()
>           assert b"resource_tracker" not in err, err.decode()
E           AssertionError: Traceback (most recent call last):
E               File "/builddir/build/BUILD/python-joblib-1.5.3-build/joblib-1.5.3/joblib/externals/loky/backend/resource_tracker.py", line 297, in main
E                 raise ValueError(
E                 ...<4 lines>...
E                 )
E             ValueError: Cannot register "REGISTER","rtype":"folder","base64_name" for automatic cleanup: unknown resource type ("L3RtcC9qb2JsaWJfbWVtbWFwcGluZ19mb2xkZXJfMTMxMl85NjA5NzRlZGMyZTU0MDM0OWYwZWM0MjVhNmVjOGQ0Nl9kM2RhZTQ5NzdiMTk0ZDE1OTM3MjUyOGMyMGE0OGMyOQ=="}). Resource type should be one of the following: ['noop', 'folder', 'file', 'semlock']

https://docs.python.org/3.15/whatsnew/3.15.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.15-b1/fedora-rawhide-x86_64/10480494-python-joblib/

For all our attempts to build python-joblib with Python 3.15, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15-b1/package/python-joblib/

Testing and mass rebuild of packages is happening in copr.
You can follow these instructions to test locally in mock if your package builds with Python 3.15:
https://copr.fedorainfracloud.org/coprs/g/python/python3.15-b1/

Let us know here if you have any questions.

Python 3.15 is planned to be included in Fedora 45.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.15.
A build failure prevents us from testing all dependent packages (transitive [Build]Requires),
so if this package is required a lot, it's important for us to get it fixed soon.

We'd appreciate help from the people who know this package best,
but if you don't want to work on this now, let us know so we can try to work around it on our side.