Re: mutex-owner Mikael Djurfeldt 10 Apr 2000 21:42 UTC

Marc Feeley <xxxxxx@IRO.UMontreal.CA> writes:

> Mutex-owner is mostly useful for debugging purposes so you can tell
> which thread is holding on to a mutex that never seems to unlock.

I agree.

> Note that there is another implementation problem: Scheme mutexes can
> be unlocked by a different thread than the owner.  Some thread systems
> don't support this (for example POSIX threads).  Fortunately, the
> semantics of mutexes proposed can be implemented with a lower-level
> mutex and a condition variable.  So supporting mutex-owner is not an
> additional overhead.

One could of course remove the ability for a different thread to
unlock the mutex, but I guess the proposed behaviour is more natural
in the kind of interactive development environment which Scheme
systems normally provide.

Thank you.