Doc/c-api: type PyInterpreterState claims GIL is shared between subinterpreters

[Oberon00]

Documentation

It seems the C API documentation for type PyInterpreterState still specifies the state before PEP 684 – A Per-Interpreter GIL / before Python 3.12:

The global interpreter lock is also shared by all threads, regardless of to which interpreter they belong.

This is wrong and if relied upon can lead to wrong behavior, especially relevant with the subinterpreters module added in 3.14 but in principle seems worth fixing in all Python versions from 3.12.

Adding a "Changed in version 3.12" infobox would be ideal.

Linked PRs

• gh-138644: docs/c-api: Fix outdated PyInterpreterState doc about shared GIL #138650
• gh-138644: Update c-api docs of PyInterpreterState about PEP-684 #138651
• [3.14] gh-138644: Update c-api docs of PyInterpreterState about PEP-684 (GH-138651) #138657
• [3.13] gh-138644: Update c-api docs of PyInterpreterState about PEP-684 (GH-138651) #138658

[AA-Turner]

PR welcomed.

A