Python 3.9

[carlwgeorge]

Hello, I'm the package maintainer for python-anyio in Fedora. Our development branch (Rawhide) has updated Python to 3.9 (pre-release versions) to get a head start on identifying issues with other Python packages. We discovered that the anyio test suite doesn't pass on 3.9.

https://bugzilla.redhat.com/show_bug.cgi?id=1817681

Another maintainer pointed out an upstream issue that introduced asyncio.loop.shutdown_default_executor.

https://bugs.python.org/issue34037#msg366812

I think this means that anyio will need changes to be compatible with Python 3.9. Here is the warning in the "What’s New In Python 3.9" document.

asyncio.loop.shutdown_default_executor() has been added to AbstractEventLoop, meaning alternative event loops that inherit from it should have this method defined. (Contributed by Kyle Stanley in bpo-34037.)

I'm not familiar enough with the code base to implement the fix myself, I just wanted to bring it to your attention. Once the fix is commited or submitted as a pull request, I can include the relevant commits as a patch in the Fedora package without waiting for a corresponding anyio release.

[agronholm]

The spawn() issue was already fixed in v1.3.0 so I'm baffled by that failure. As for the exception about asyncio.loop.shutdown_default_executor, that happens because asyncio broke backwards compatibility by introducing a mandatory new method which uvloop has not implemented yet.

[agronholm]

I only get 5 failures when testing against Python 3.9.0b1. Aside from the uvloop related problems, the remaining one is something I should look into.

[encukou]

I filed a Python issue to reconsider making shutdown_default_executor mandatory: https://bugs.python.org/issue40802

[agronholm]

I've created a ticket in uvloop: MagicStack/uvloop#349

[agronholm]

I've released AnyIO 1.3.1 which includes this workaround.

[carlwgeorge]

Thank you for the quick fix and release. It allowed me to update the Fedora package and clear the build failure.