Free-threading support

[merlinz01]

What's the status of free-threading support for this project?

Linking #1662

[aaugustin]

As far as I can tell, I just need to add some boilerplate to the C extension, and then it should work.

[aaugustin]

Rationale:

• The C extension exposes only functions that take arguments and return results; there are no classes, no state, nothing that can be called concurrently. I just need to declare that it's safe.
• To the best of my understanding, everything written in pure Python should Just Work™️ ?

If you're familiar with free-threaded Python and you can give me the manual for library maintainers wanting to be compatible, that will help :-)

[merlinz01]

If you're familiar with free-threaded Python

I'm not very familiar with the low-level parts, but I think your rationale above is correct as long as there aren't implicit assumptions about the GIL protecting state in either native or pure Python code. Adding free-threading Python to your CI test matrix would provide a starting point for knowing if there are things that need changed.

the manual for library maintainers wanting to be compatible

See https://py-free-threading.github.io/porting-extensions/
and https://docs.python.org/3/howto/free-threading-python.html