[lucidyan]

Are we talking about "PEP 554 – Multiple Interpreters in the Stdlib"[1] proposal?

[1] https://peps.python.org/pep-0554/

[kzrdude]

Yes and https://peps.python.org/pep-0684/ which is no longer a proposal, but it's also been implemented in CPython 3.12.

with PoC of the parallelization code being developed here https://github.com/jsbueno/extrainterpreters