Document the thread safety of `functools.lru_cache`

[pfmoore]

Documentation

The documentation doesn't state whether functools.lru_cache (and decorators derived from it like functools.cache) are thread safe, meaning that it's not clear that it's safe to (for example) populate the cache by running the function in multiple threads. The comments in the source code certainly imply that it's intended to be thread safe, but I'll admit I haven't double checked all the details.

Can the thread safety be made explicit in the docs?

Linked PRs

• [3.11] GH-93179: Document the thread safety of functools.lru_cache (GH-95970) #100512