异步 ThreadPool

线程池是单例，一个进程里只有一个线程池

private void btnThreadPool_Click(object sender, EventArgs e)
        {
            Stopwatch watch = new Stopwatch();
            watch.Start();
            Console.WriteLine();
            Console.WriteLine("****************btnThreadPool_Click Start 主线程id={0}*****************", Thread.CurrentThread.ManagedThreadId);
            List<ManualResetEvent> mreList = new List<ManualResetEvent>();
            for (int i = 0; i < 5; i++)
            {
                int b = i;
                mreList.Add(new ManualResetEvent(false));
                WaitCallback method = t =>
                {
                    this.TestThreadWithoutReturn(string.Format("btnThreadPool_Click_{0}", b));
                    Console.WriteLine("我是回调 btnThreadPool_Click_{0}", b);
                    mreList[b].Set();
                };
                ThreadPool.QueueUserWorkItem(method);

                //WaitCallback method = t =>  this.TestThreadWithoutReturn(t.ToString ());
                //ThreadPool.QueueUserWorkItem(method, string.Format("btnThreadPool_Click_{0}", b));
            }

        private void TestThreadWithoutReturn(string name)
        {
            Console.WriteLine("TestThread Start Name={2},当前线程的id:{0},当前时间为{1}", Thread.CurrentThread.ManagedThreadId, DateTime.Now.ToString("hh:mm:ss:fff"), name);
            long Sum = 0;
            for (int i = 1; i < 999999999; i++)
            {
                Sum += i;
            }
            //Thread.Sleep(2000);
            Console.WriteLine("TestThread End Name={2},当前线程的id:{0},当前时间为{1}", Thread.CurrentThread.ManagedThreadId, DateTime.Now.ToString("hh:mm:ss:fff"), name);
        }