Change RLock from factory function to actual type, remove dead Python RLock implementation

Feature or enhancement

Proposal:

Currently in CPython threading.RLock is a factory function that returns a new RLock instance. It either returns an instance of _CRLock, if it's defined, otherwise it returns an instance of _PyRLock. I'm kidding--in practice, it never returns _PyRLock. You'd have to do something silly (threading._CRLock = None) in order to get it to return an instance of _PyRLock, because these days _CRLock is always defined.

I haven't gone reading through old versions / git blame / etc, but my guess is that CPython used to support platforms that didn't have a native RLock, or the C implementation of RLock was unsuitable for some reason on some platforms. Here in 2025 I find the C implementation of RLock is unguarded by any #if / #ifdef statement. All platforms currently supported by CPython must support threading, the C version of RLock (_thread.RLock) is always defined, and the threading.RLock factory function always returns an instance of that object (unless you do something silly).

Assuming I'm right about all that:

• The Python implementation of RLock (class _RLock) in Lib/threading.py is dead code and should be removed.
• There's no longer any point in making threading.RLock a factory function. (Was there ever a point?) threading.RLock should simply be an alias for the RLock implementation in C (_thread.RLock).

Has this already been discussed elsewhere?

No response given

Links to previous discussion of this feature:

No response

Linked PRs

• gh-141462
• gh-142977

Bắt đầu với Lib/threading.py và entry point _thread.RLock, sau đó xem lại các cuộc thảo luận PR được liên kết trước khi thực hiện thay đổi. Xác nhận rằng alias và việc xóa được đề xuất tương thích với các nền tảng được hỗ trợ và hành vi threading hiện có; hoàn tất nghĩa là triển khai _RLock không còn được sử dụng đã được xóa và threading.RLock trực tiếp tham chiếu đến triển khai C.