asp.net .net4.0使用异步编程

  string a = "";
            Action<object> ac = (object obj) =>
            {
                Debug.WriteLine("睡眠开始:" + DateTime.Now);
                Thread.Sleep();
                Debug.WriteLine("睡眠结束:" + DateTime.Now);
                Debug.WriteLine(obj.ToString());
            };
            Task.Factory.StartNew(ac, a);
            Response.Write("执行完毕");
            Response.End();