public class Global : System.Web.HttpApplication
    {
        private static event Action eventActions;
        /// <summary>
        ///  当前正在运行的异步线程池
        /// </summary>
        private static Dictionary<string, IAsyncResult> diyAsync = new Dictionary<string, IAsyncResult>();
        protected void Application_Start(object sender, EventArgs e)
        {
            eventActions += MyClass.Writer;//任务(可以处理多个方法)
            System.Timers.Timer aTimer = new System.Timers.Timer();
            aTimer.Elapsed += new System.Timers.ElapsedEventHandler(OnTimedEvent);
            aTimer.Interval = 200;
            aTimer.Enabled = true;
        }
        /// <summary>
        /// 定时执行任务
        /// </summary>
        /// <param name="source"></param>
        /// <param name="e"></param>
        private static void OnTimedEvent(object source, ElapsedEventArgs e)
        {
            foreach (Action action in eventActions.GetInvocationList())
            {
                try
                {
                    if (diyAsync.Any(p => p.Key == action.Method.Name) && !diyAsync[action.Method.Name].IsCompleted)
                        continue;
                    diyAsync[action.Method.Name] = action.BeginInvoke(null, null);
                }
                catch (Exception ex)
                {
                    //任务执行出错
                }
            }
        }
        protected void Session_Start(object sender, EventArgs e)
        {
            string name = System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
        }

        protected void Application_BeginRequest(object sender, EventArgs e)
        {
           string name=System.Reflection.MethodBase.GetCurrentMethod().Name;
           WH_WriteLog.WriteLog(name);
        }

        protected void Application_AuthenticateRequest(object sender, EventArgs e)
        {
            string name=System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
        }

        protected void Application_Error(object sender, EventArgs e)
        {
            string name = System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
            WH_WriteLog.WriteLog(e.ToString());
        }

        protected void Session_End(object sender, EventArgs e)
        {
            string name = System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
        }

        protected void Application_End(object sender, EventArgs e)
        {
            string name = System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
        }
    }

    public class MyClass
    {
        public static void Writer()
        {
            string name = System.Reflection.MethodBase.GetCurrentMethod().Name;
            WH_WriteLog.WriteLog(name);
        }
    }