Bug 2326927

python-redis fails to build with Python 3.14.0a1.

____________________ TestMultiprocessing.test_redis_client _____________________

self = <tests.test_multiprocessing.TestMultiprocessing object at 0x7fd603bd6c50>
r = <redis.client.Redis(<redis.connection.ConnectionPool(<redis.connection.Connection(host=localhost,port=6379,db=0)>)>)>

    def test_redis_client(self, r):
        "A redis client created in a parent can also be used in a child"
        assert r.ping() is True
    
        def target(client):
            assert client.ping() is True
            del client
    
        proc = multiprocessing.Process(target=target, args=(r,))
>       proc.start()

tests/test_multiprocessing.py:163: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
/usr/lib64/python3.14/multiprocessing/process.py:121: in start
    self._popen = self._Popen(self)
/usr/lib64/python3.14/multiprocessing/context.py:224: in _Popen
    return _default_context.get_context().Process._Popen(process_obj)
/usr/lib64/python3.14/multiprocessing/context.py:300: in _Popen
    return Popen(process_obj)
/usr/lib64/python3.14/multiprocessing/popen_forkserver.py:35: in __init__
    super().__init__(process_obj)
/usr/lib64/python3.14/multiprocessing/popen_fork.py:20: in __init__
    self._launch(process_obj)
/usr/lib64/python3.14/multiprocessing/popen_forkserver.py:47: in _launch
    reduction.dump(process_obj, buf)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

obj = <Process name='Process-9' parent=996 initial>
file = <_io.BytesIO object at 0x7fd5f82ebb50>, protocol = None

    def dump(obj, file, protocol=None):
        '''Replacement for pickle.dump() using ForkingPickler.'''
>       ForkingPickler(file, protocol).dump(obj)
E       _pickle.PicklingError: Can't pickle local object <function TestMultiprocessing.test_redis_client.<locals>.target at 0x7fd5f829efb0>
E       when serializing dict item '_target'
E       when serializing multiprocessing.context.Process state
E       when serializing multiprocessing.context.Process object

/usr/lib64/python3.14/multiprocessing/reduction.py:60: PicklingError

This is caused by the change of the default process starting method in multiprocessing (https://docs.python.org/dev/whatsnew/3.14.html#multiprocessing):

The default start method (see Contexts and start methods) changed from fork to forkserver on platforms other than macOS & Windows where it was already spawn. If you require the threading incompatible fork start method you must explicitly request it using a context from multiprocessing.get_context() (preferred) or change the default via multiprocessing.set_start_method(). (Contributed by Gregory P. Smith in gh-84559.)


https://docs.python.org/3.14/whatsnew/3.14.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.14/fedora-rawhide-x86_64/08257928-python-redis/

For all our attempts to build python-redis with Python 3.14, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/package/python-redis/

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 3.14:
https://copr.fedorainfracloud.org/coprs/g/python/python3.14/

Let us know here if you have any questions.

Python 3.14 is planned to be included in Fedora 43.
To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.14.
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.