private static System.Threading.Timer s_Timer;
        static void Main()
        {
            Console.WriteLine("checking status every 2 seconds");
            s_Timer = new System.Threading.Timer(Status, null, Timeout.Infinite, Timeout.Infinite);
            s_Timer.Change(
 
2000, Timeout.Infinite);
            Console.ReadKey();
        }
        private static void Status(object state)
        {
            Console.WriteLine("in status at {0}", DateTime.Now);
            Thread.Sleep(1000);
            //返回前讓timer 2s 後再觸發
            s_Timer.Change(2000, Timeout.Infinite);
        }
 

        static void Main()
        {
            Console.WriteLine("checking status every 2 seconds");
            Status();
            Console.ReadKey();
        }
        private static async void Status()
        {
            while (true)
            {
                Console.WriteLine(
 
"in status at {0}", DateTime.Now);
                //要檢查的程式碼
                //在迴圈末尾，在不阻塞執行緒的前提下延遲2s
                await Task.Delay(2000);     //await 允許執行緒返回
                //2s 之後，某個執行緒會在await之後介入並繼續迴圈
            }
        }