unicode: make ucnhash_capi initialization thread-safe in `--disable-gil` builds

[colesbury]

Feature or enhancement

The _PyUnicode_Name_CAPI provides functions to get the name for a given Unicode character code and vice versa. It is lazily initialized and stored in the per-interpreter _Py_unicode_state:

cpython/Include/internal/pycore_unicodeobject.h

Lines 425 to 432 in 3932b0f

	struct _Py_unicode_state {
	struct _Py_unicode_fs_codec fs_codec;
	_PyUnicode_Name_CAPI *ucnhash_capi;
	// Unicode identifiers (_Py_Identifier): see _PyUnicode_FromId()
	struct _Py_unicode_ids ids;
	};

The initialization of the ucnhash_capi isn't thread-safe without the GIL. (There can be a data race on reading and writing ucnhash_capi).

Mostly for my own reference, here are the similar modifications in the nogil-3.12 fork: colesbury/nogil-3.12@5d006db9fa

Linked PRs

• gh-111972: unicode: Make ucnhash_capicapsule initialization thread-safe #112249

[Eclips4]

This seems quite easy 😄
Please, take a look at the #112249.

[erlend-aasland]

Resolved by #112249