Possible issue with mutexes

[Herwig Hochleitner <herwig@bendlas.net>]

Hello,

I've recently created a semaphore type, based on mutex and condition 
vars, for controlling parallelism in an elisp processor.

The project went well, so far, but now that I attempted to pull out this 
semaphore implementation and create a test for it, I've noticed 
behavior, that leads me to believe, that emacs' thread and mutex 
guarantees might not hold in all cases.

When running the [test 
case](https://github.com/webnf/semaphore.el/blob/306d5a84b99526213c3a7d367f8d8041961ea52a/test/emacs-semaphore-test.el), 
you would expect `test/semaphore/active-count` to be 0 at the end of a 
run, right? For me, it's wildly inconsistent at the end of a run and 
seems to become desynchronized among worker threads. In this [example 
run](https://hastebin.com/wigiwizabi.log) from my machine, it happens to 
settle at 10.

Am I doing this wrong, somehow?

If not, could somebody help me file a report? First post on this ML ...

kind regards