Bug 2155496

Summary: Cython fails to build with Python 3.12: RuntimeError: There is no current event loop in thread 'MainThread'.
Product: [Fedora] Fedora Reporter: Tomáš Hrnčiar <thrnciar>
Component: CythonAssignee: Tomáš Hrnčiar <thrnciar>
Status: CLOSED RAWHIDE QA Contact: Fedora Extras Quality Assurance <extras-qa>
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Version: rawhideCC: igor.raits, mhroncok, ndbecker2, pviktori, python-packagers-sig, steve.traylen, thrnciar, torsava, zbyszek
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Last Closed: 2023-02-23 08:13:54 UTC Type: Bug
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Bug Blocks: 2135404, 2155429    

Description Tomáš Hrnčiar 2022-12-21 11:00:42 UTC
Cython fails to build with Python 3.12.0a3.

Traceback (most recent call last):
  File "/builddir/build/BUILD/cython-0.29.32/TEST_TMP/0/run/py35_asyncio_async_def/main.py", line 9, in <module>
    with closing(asyncio.get_event_loop()) as loop:
                 ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/lib64/python3.12/asyncio/events.py", line 676, in get_event_loop
    raise RuntimeError('There is no current event loop in thread %r.'
RuntimeError: There is no current event loop in thread 'MainThread'.

asyncio.get_event_loop() and many other asyncio
functions like ensure_future(), shield() or gather(), and also the
get_event_loop() method of BaseDefaultEventLoopPolicy now raise a RuntimeError
if called when there is no running event loop and the current event loop was
not set. Previously they implicitly created and set a new current event loop.
DeprecationWarning is no longer emitted if there is no running event loop but
the current event loop is set in the policy. (Contributed by Serhiy Storchaka
in gh-93453.)

https://github.com/python/cpython/issues/93453

https://docs.python.org/3.12/whatsnew/3.12.html

For the build logs, see:
https://copr-be.cloud.fedoraproject.org/results/@python/python3.12/fedora-rawhide-x86_64/05157645-Cython/

For all our attempts to build Cython with Python 3.12, see:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/package/Cython/

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 3.12:
https://copr.fedorainfracloud.org/coprs/g/python/python3.12/

Let us know here if you have any questions.

Python 3.12 is planned to be included in Fedora 39. To make that update smoother, we're building Fedora packages with all pre-releases of Python 3.12.
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.

Comment 1 Miro Hrončok 2022-12-21 12:00:54 UTC
Upstream issue: https://github.com/cython/cython/issues/5183

In the meantime, I think the tests can be excluded if this is blocking anything.

Comment 2 Tomas Orsava 2023-02-01 13:27:23 UTC
PR: https://src.fedoraproject.org/rpms/Cython/pull-request/39

Waiting for branching.

Comment 3 Ben Cotton 2023-02-07 15:13:14 UTC
This bug appears to have been reported against 'rawhide' during the Fedora Linux 38 development cycle.
Changing version to 38.

Comment 4 Zbigniew Jędrzejewski-Szmek 2023-02-22 13:10:33 UTC
(In reply to Tomas Orsava from comment #2)
> Waiting for branching.

Branching has happened ;)

Comment 5 Miro Hrončok 2023-02-22 13:31:44 UTC
Indeed. Tomáš, could you please rebase https://src.fedoraproject.org/rpms/Cython/pull-request/39 ?

Comment 6 Tomáš Hrnčiar 2023-02-23 06:41:17 UTC
Patches included in this PR are a part of 0.29.33 release. I'll will investigate the other problems with Cython and Python 3.12.