title: Does a call to unlock a mutex necessarily switch to another thread that was blocked on the lock?
body: <p>Let's say we have two threads: th1 and th2.</p>
  
  <p>Let's imagine this line of events:</p>
  
  <ol>
  <li><p>Th1 locks the mutex and does some work in it's critical region.</p></li>
  <li><p>Th2 calls lock on the mutex but is blocked.</p></li>
  <li><p>Th1 finishes its work on the critical region and unlocks the mutex.</p></li>
  </ol>
  
  <p>My question now is: Even if th1 still had some time left to work, will the call to unlock the mutex necessarily cause an immediate context switch to a thread that is blocked on the lock(in this case to th2) if there's any?</p>