It is mentioned in the Threads.nthreads docs, and also listed in doc/src/base/multi-threading.md so this seems reasonable?

@vtjnash reacted with a 👎 perhaps you could elaborate what your concerns are?

There are almost no uses of this outside of internal scheduler code that are not subtle races and UB if you access this value

OK, I find it a convincing argument that this should not be merged.

But then any docstrings of exported/public bindings referencing maxthreadid should likely also be adjusted to not do that anymore.

The only docstring I found referencing maxthreadid (besides its own docstring) is that of Threads.nthreads, but there it seems straight-forward to excise it... Did I miss anything?

Merge?