I think this is bad advice generally. My experience with yield() is that it just eats CPU, as it is a noop at least on some versions of Linux (I don't know about Windows, as I don't go there anymore).

Under Linux, each thread has its own pid (although it's pretty tricky to get it: this is basically the only XS functionality needed by Thread::Signal). So you are able to use POSIX::nice on that platform.

BrowserUK has been looking at setting priority of threads on Windows, but as he has described in several nodes in this thread, the problem is interfacing between what Perl thinks threads are and what the OS thinks threads are.

In a non-event driven situation, I would probably use a lock(), cond_wait() and cond_signal() combo by which threads tell each other something has happened or needs to be done. But obviously, that is a bit tricky doing from the Tk event loop.

Liz