计时器不跨线程工作 [英] Timer is not working in cross threads

问题描述

我有2个全球 System.Windows.Forms.Timer 在我的格式即可。无论在形式的构造函数初始化。但尚未启动。构造函数启动新线程并线程允许并启动这两个定时器。显然，这是一切的跨线程，但它不抛出任何跨线程异常。但它甚至不工作。它不火的 Timer.Tick 方法。下面是代码：

I have 2 global System.Windows.Forms.Timer in my form. Both are initialized in form's constructor. But not started yet. Constructor starts a new thread and that thread enables and starts both of the timers. Obviously it is all cross threading, but it doesn't throw any cross-thread exception. But it doesn't even work. It does not fire the Timer.Tick method. Here is the code:

第1种方法：

在表单构造：

    KeepMeAliveTimer = new Timer();  //timer 1
    KeepMeAliveTimer.Interval = 15000;            
    KeepMeAliveTimer.Tick += KeepMeAlive;
    timer1 = new Timer();   //timer 2
    timer1.Interval = 15000;
    timer1.Tick += timer1_Tick;
    //started a new thread

在新THEAD：

    //after performing some tasks, it enables the timers
    KeepMeAliveTimer.Enabled = true;  //timer 1
    KeepMeAliveTimer.Start();
    timer1.Enabled = true;   //timer 2
    timer1.Start();

但它不发射了计时器的Tick事件，甚至不扔任何异常。

But it is not firing up Timer's tick events and not even throwing any exception.

第2种方法：

但是，当我初始化并启用了定时器在同一个线程（主线程），它们是完全工作：

But when I initialized and enabled the Timers in the same thread (Main Thread) they are working perfectly:

    KeepMeAliveTimer = new Timer();   //timer 1
    KeepMeAliveTimer.Interval = 15000;            
    KeepMeAliveTimer.Tick += KeepMeAlive;
    KeepMeAliveTimer.Enabled = true;
    KeepMeAliveTimer.Start();
    timer1 = new Timer();    //timer 2
    timer1.Interval = 15000;
    timer1.Tick += timer1_Tick; 
    timer1.Enabled = true; 
    timer1.Start();  

现在的问题是;为什么第一种方法是行不通的，如果竟然没有任何异常？

Now the question is; Why the first method is not working if there is not even any exception?

推荐答案

Timer类是线程安全的，但不你期望的方式。在调用工作线程的start（）方法并真正开始计时。类经过创建隐藏的窗口，因此它可以调用SetTimer的WINAPI功能并且当完成接收所述WM_TIMER消息的努力。

The Timer class is thread-safe but not in the way you expect it. Calling the Start() method on worker thread does actually start the timer. The class goes through the effort of creating a hidden window so it can call the SetTimer winapi function and receive the WM_TIMER message when it is done.

但Tick事件不能提高。你不会，你肯定没有在该线程调用Application.Run（）。因此，应在开始工作线程的计时器。必要时使用Control.BeginInvoke得到它开始在UI线程上。

But the Tick event cannot be raised if nobody is listening for that message. You won't be, surely you didn't call Application.Run() on that thread. You should therefore not start a timer on a worker thread. Use Control.BeginInvoke if necessary to get it started on the UI thread.

或者使用System.Threading.Timer或者System.Timers.Timer，他们不依赖于消息循环。你必须正确地互锁，他们已用事件或回调运行还的其他的线程。这是什么样的解决方案，往往会造成另一个问题。

Or use a System.Threading.Timer or System.Timers.Timer, they don't depend on a message loop. You do have to interlock properly, their Elapsed event or callback run on yet another thread. Which is the kind of solution that tends to create another problem.

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