Avoiding Deadlocks

• Waiting thread is blocked
• Condition object manages set of threads that wait for the condition to change
  
• To unblock, another thread must call signalAll on the same condition object
• Call when state changes
  

  public E remove()
  {
     . . .
     E r = elements[head];
     . . .
     spaceAvailableCondition.signalAll(); // Unblock waiting threads
     return r;
  }
  

• All waiting threads removed from wait set, unblocked
• Ch9/queue2/BoundedQueue.java