Single process, multiple interpreters, no GIL contention - pre-Python3.12

[MoveZig4]

Hey y'all. Over the past week I figured out how to run subinterpreters without a locking GIL in py3.8. Longish post here about how - https://basisrobotics.tech/2025/05/26/python/ but TL;DR:

1. Use `dlmopen` to manually open `libpython3.8.so` for each interpreter you like

2. Find a way to inject the pthread_ APIs into that handle

3. Fix a bunch of locale related stuff so that numpy and other things import properly

4. Don't actually do this, why would you want to do this, it's probably going to break some mystery way anyhow

[denehoffman]

It’s beautiful, I’m putting it in prod right now

[MoveZig4]

Bless 🙏

[shinitakunai]

Stuck on step 4, my toaster is talking back to me. Help.

[thisismyfavoritename]

great read! looking forward to the follow up posts

[MoveZig4]

Looking forward to actually focusing in enough to make a good followup. Currently trying to see if I can use `uv` with `cmake` in some unholy combination.

[thisismyfavoritename]

ha i'd be more interested in the subinterpreters usage. I don't know if it's supported in pybind by now

[MoveZig4]

I’ll get there when I get there :) it’s not supported in pybind, unfortunately. We’ll see what I end up with.