(Experimental) support of the nogil fork of CPython

[thejcannon]

👋 love PyO3!
We have a use case for trying out the nogil fork of CPython (https://github.com/colesbury/nogil-3.12/tree/nogil-3.9) but I don't think we'll get very far until we refactor and recompile our code which relies heavily on PyO3.

I can't say I understand the impact at any level, but thought I'd throw this on the radar and get the conversation going.

[adamreichold]

Please have a look at #2885 where some conservation on this has already happened.

[thejcannon]

Weird I didn't find anything when GitHub searching for "nogil" we can close as duplicate

[thejcannon]

Ah I was only searching issues, not PRs

[adamreichold]

No worries. Maybe you can use the code proposed in the PR can be brought to bear onto your use case. Ideally after a rebase though.

[thejcannon]

Luckily we sidestep the "library" issue with nogil, since we're shipping a python binary and application.

We all are just using pyo3 to consume frozen dataclasses (with possible references to other frozen dataclasses) run some rust code on the data, then construct and return other frozen dataclasses. In a pool of threads.

Since we aren't mutating objects, I suspect nogil will cause much less contention in the threads, so I'm excited to try it out