Feature or enhancement

The Modules/_json.c parser is mostly stateless (or the state is immutable). The one exception is the "memo" dictionary, which is used to avoid duplicate PyUnicodeObject instances for the same JSON C strings.

The memo dictionary is already cleared after each call scan_once:

We should move the creation and destruction of the memo dict to the invocation of scan_once instead of having it as part of the module state. This will avoid contention on the dictionary locks in --disable-gil builds if multiple threads are concurrently parsing JSON strings.

For an example modification, see colesbury/nogil-3.12@964bb33962.

Linked PRs

• gh-111928: make "memo" dict local to scan_once call #112005