c# AutoResetEvent 控制线程暂停，恢复的问题


 public delegate void WorkThreadHandler();
   
    public class WorkThread
    {
        public event WorkThreadHandler OnWorkdThreadEvent;        EventWaitHandle _wh = new AutoResetEvent(false);
        Thread _worker;
        private bool _isRun=false;        public void DoWork()
        {
            while (true)
            {
                if (_isRun)
                {
                    WorkThreadHandler handler = OnWorkdThreadEvent;
                    if (handler != null) handler();
                }
                else
                {
                    _wh.WaitOne();
                }
            }
        }        public void Start()
        {
            _worker = new Thread(DoWork);
            _worker.Start();
        }        public void Resume()
        {
            _isRun = true;
            _wh.Set();
        }        public void Suspend()
        {
            _isRun = false;
            _wh.WaitOne();
        }        public void Stop()
        {
            _isRun = true;
            _wh.Close();
        }
    }不想采用过时的Suspend，Resume来控制线程，自己写了如上的一个类
可是不知道为什么通过对应的方法无法起到控制的作用....
求解。