Flash actionscript3.0 多个setTimeout之间会顺序执行 单线程执行 无法中止

private var index:int;
private var stop:Boolean = false;

public function EffectTest()
{
       setTimeout(run, 200);
       setTimeout( function():void
       {
               trace("try to terminate running");
              stop = true;
       }, 500);
       setTimeout( function():void
       {
               trace("index is", index);
       }, 600);
}

protected function run(): void
{
        //this loop needs 1.3s to finish
        for (var i:int = 0; i < 10000000; i++)
       {
               if (stop)
              {
                     index = i;
                      trace("running has been terminated");
                      return;
              }
               var a:Number = Math.sqrt(i);
       }
       index = i;
        trace("finish running");
}