执行期间定时事件重叠

本文关键字：重叠 事件 定时 执行期 | 更新日期: 2023-09-27 17:59:15

我使用一个服务执行自动化任务时遇到问题。该服务使用计时器，并在20秒后执行。

执行的函数打开数据库，从中读取，通过网络发送值，接收响应并用该响应更新数据库。

它一直运行良好，直到我想对数据库中大约1000行执行自动化任务，但系统"失败"。在检查日志后，我发现该函数在间隔之后执行，即使前一个实例仍在执行。该功能应该发送一条消息，一些客户抱怨没有收到消息，而另一些客户则收到了多达六次的消息。

如果前一个实例仍在运行，是否有任何简单有效的方法可以确保函数不会运行。

如果我在函数中启动和停止时间，它只会将"已通过"的时间添加到间隔

这是代码

public partial class Service1 : ServiceBase
{
    private Timer timer1 = null;
    public Service1()
    {
        InitializeComponent();
    }
    protected override void OnStart(string[] args)
    {
        timer1 = new Timer();
        this.timer1.Interval = 20000;
        this.timer1.Elapsed += new  System.Timers.ElapsedEventHandler(this.timer1_Tick);
        timer1.Enabled = true;
        Library.WriteErrorLog("service has started");
    }
    private void timer1_Tick(object sender, ElapsedEventArgs e)
    {
        try
        {
        //retrieve data from database
        //read rows
        //Loop through rows
        //send values through network
        //receive response and update db
        }
        catch (Exception ex)
        {
            Library.WriteErrorLog(ex);
        }
    }
}
    protected override void OnStop()
    {
        timer1.Enabled = false;
        Library.WriteErrorLog("service has stopped");
    }
}

执行期间定时事件重叠

private void timer1_Tick(object sender, ElapsedEventArgs e)
{
    Timer timer = sender as Timer;
    timer.Enabled = false;  // stop timer
    try
    {
         //retrieve data from database
         //read rows
         //Loop through rows
         //send values through network
         //receive response and update db
     }
     catch (Exception ex)
     {
         Library.WriteErrorLog(ex);
     }
     finally
     {
         timer.Enabled = true;   // start timer again, no overlapping
     }
 }

您使用的是多线程System.Timers.Timer，它在每个Elapsed事件上从ThreadPool调用新线程上的timer1_Tick回调。使用变量来同步执行。

   public partial class Service1 : ServiceBase
    {
        private Timer timer1 = null;
        private long isTaskRunning = 0;
        public Service1()
        {
            InitializeComponent();
        }
        protected override void OnStart(string[] args)
        {
            timer1 = new Timer();
            this.timer1.Interval = 20000;
            this.timer1.Elapsed += new  System.Timers.ElapsedEventHandler(this.timer1_Tick);
            timer1.Enabled = true;
            Library.WriteErrorLog("service has started");
        }
        private void timer1_Tick(object sender, ElapsedEventArgs e)
        {
            try
            {
            if (Interlocked.CompareExchange(ref isTaskRunning, 1, 0)==1)
            {
             return;
            }
            //retrieve data from database
            //read rows
            //Loop through rows
            //send values through network
            //receive response and update db
            }
            catch (Exception ex)
            {
                Library.WriteErrorLog(ex);
            }
            finally
            {
             Interlocked.Exchange(ref isTaskRunning, 0);
            }
        }
    }
        protected override void OnStop()
        {
            timer1.Enabled = false;
            Library.WriteErrorLog("service has stopped");
        }
    }
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