Feature or enhancement

The collections.deque object has mutable internal state that would not be thread-safe without the GIL. We should use the critical section API to make it thread-safe. I think it might be cleanest to first convert most of the deque implementation to Argument Clinic and use the @critical_section directive rather than writing the critical sections manually.

Mostly for my own reference, here is the implementation from nogil-3.12: colesbury/nogil-3.12@f1e4742eaa. That implementation did not use the critical section API, which made it more complicated.

Depends on: #111903

Linked PRs

• gh-112050: Make collections.deque thread-safe in free-threaded builds #113830
• gh-112050: Convert most methods on collections.deque to use Argument Clinic #113963