AutoResetEvent

        AutoResetEvent autoEvent = new AutoResetEvent(true);        
        public void DowlLoadIds()
        {
            bool f = autoEvent.Set();
            for (int i = 0; i < 30; i++)
            {
                //System.Threading.Thread t = new Thread(delegate() { DownIdCallBack(autoEvent); });
                //t.Start();
                TimerCallback timerDelegate = new TimerCallback(DownIdCallBack);
                System.Threading.Timer t = new System.Threading.Timer(timerDelegate, autoEvent, 0, 200);
            }
        }

        int i = 0;
        private void DownIdCallBack(object o)
        {
            var autoEvent = (AutoResetEvent)o;
            autoEvent.WaitOne();
            //System.Threading.Interlocked.Increment(ref i);
            i++;
            if (i > 20)
            {
                i = 0;
                autoEvent.Reset();
                //autoEvent.WaitOne();
                return;
            }
            //Trace.WriteLine(System.DateTime.Now.ToString());
            Trace.WriteLine(i.ToString());
            autoEvent.Set();
        }