When is pthread_spin_lock the right thing to use (over e.g. a pthread mutex)?

Question

Given that pthread_spin_lock is available, when would I use it, and when should one not use them ?

i.e. how would I decide to protect some shared data structure with

Answer 1

The spinlock is a "busy waiting" lock. It's main advantage is that it keeps the thread active and won't cause a context switch, so if you know that you will only be waiting for a very short time (because your critical operation is very quick), then this may give better performance than a mutex. Conversely a mutex will cause less demand on the system if the critical section takes a long time and a context switch is desirable.

TL;DR: It depends.