title: When is a good idea to use a spinlock?
body: <p>It seems that spinlocks aren't that great as they waste CPU cycles when the are waiting (blocking).
  If the thread just goes to sleep while waiting for a signal to wakeup, then CPU cycles aren't lost while spinning.</p>
  
  <p>Maybe it is good to use a spinlock if the locks are held for a very short time, then maybe it uses less time?  If this is true why?</p>