GameMonkeyScript/gmsrc/doc/tutorial/2-continuing/scripts/blocking_01.gm

/*
  Yield based thread looping - bad!
*/

global WakeUp = false;

global thread_1 = function( a_count )
{
  while (WakeUp == false)
  {
    // Snooze
    print("zzz");
    yield();
  }
  
  print("I just woke up, boy was I tired!");
  
};

// Launch thread
thread( thread_1 );
// Sleep for 1 secs then set the wakeup variable
sleep(1);

WakeUp = true;