Mutexes are the gold standard for this kind of thing. If you have really excessive contetion, you could create a control or "scheduling" thread. It handles mutex contention issues by queuing requests, setting conditions, and calling pthread_cond_signal() to wake a thread. Unless this is what you meant by "signal".

Do you have a copy of Richard Stevens book? -- 'Advanced Programming in the UNIX Environment'

It covers all of these topics.

If you're using Linux, pthread had some issues before kernel 2.6 release, and pthread_cond_signal was one of them, if I remember correctly. It may still have other issues. I don't know. I don't code in Linux very often.