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我试图用 Rx 扩展解决方案来回答另一个问题。在制作解决方案时，我发现了一些奇怪的东西。

static Random rand = new Random();

static void Main(string[] args) {
    //var obs = Observable.Interval(TimeSpan.FromMilliseconds(250)).Do<long>(i =>
    var obs = Observable.Interval(TimeSpan.FromMilliseconds(25)).Do<long>(i =>
    {
        CancellationTokenSource source = new CancellationTokenSource(25);
        //CancellationTokenSource source = new CancellationTokenSource(250);
        ReadNext(source.Token, i);
    }).Publish();
    var disp = obs.Connect();
    Console.ReadKey();
    disp.Dispose();
    Console.ReadKey();
}

static private void ReadNext(CancellationToken token, long actual) {
    int i = rand.Next(4);
    Stopwatch watch = new Stopwatch();
    watch.Start();
    for(int j = 0; j < i; j++) {
        //Thread.Sleep(100);
        Thread.Sleep(10);
        if(token.IsCancellationRequested) {
            Console.WriteLine(string.Format("method cancelled. cycles: {0}, should be 3. Now should be last (2): {1}", i, j));
            return;
        }
    }
    Console.WriteLine(string.Format("method done in {0} cycles. Preserved index: {1}. Elapsed time: {2}", i, actual, watch.ElapsedMilliseconds));
    watch.Stop();
}

取消超时有问题。不知何故，当第三个周期发生时（我们已经等待了大约 30 毫秒），ReadNext并不是每次都取消。

查看打印输出：

method done in 1 cycles. Preserved index: 7. Elapsed time: 9
method done in 1 cycles. Preserved index: 8. Elapsed time: 9
method done in 0 cycles. Preserved index: 9. Elapsed time: 0
method cancelled. cycles: 3, should be 3. Now should be last (2): 2
method done in 1 cycles. Preserved index: 11. Elapsed time: 9
method done in 2 cycles. Preserved index: 12. Elapsed time: 19
method done in 2 cycles. Preserved index: 13. Elapsed time: 19
method done in 0 cycles. Preserved index: 14. Elapsed time: 0
method done in 2 cycles. Preserved index: 15. Elapsed time: 19
method done in 0 cycles. Preserved index: 16. Elapsed time: 0
method done in 1 cycles. Preserved index: 17. Elapsed time: 9
method cancelled. cycles: 3, should be 3. Now should be last (2): 2
method done in 1 cycles. Preserved index: 19. Elapsed time: 9
method done in 3 cycles. Preserved index: 20. Elapsed time: 29  <- bug.
method done in 2 cycles. Preserved index: 21. Elapsed time: 19
method done in 1 cycles. Preserved index: 22. Elapsed time: 9
method done in 1 cycles. Preserved index: 23. Elapsed time: 9
method done in 2 cycles. Preserved index: 24. Elapsed time: 19
method done in 2 cycles. Preserved index: 25. Elapsed time: 19
method done in 2 cycles. Preserved index: 26. Elapsed time: 19
method done in 1 cycles. Preserved index: 27. Elapsed time: 10
method done in 1 cycles. Preserved index: 28. Elapsed time: 9
method done in 3 cycles. Preserved index: 29. Elapsed time: 29  <- bug.
method done in 1 cycles. Preserved index: 30. Elapsed time: 9

我是否必须听取其他调度程序，以确保在 25 毫秒后取消令牌肯定会被取消，或者其他导致错误的原因？

编辑

如果我将睡眠顺序升级一个（检查上面的注释代码），它就可以工作。问题在于Thread.Sleep不够精确。

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1 回答 1

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Windows 不是实时操作系统。一般来说，系统定时器以 60Hz 运行，这意味着它们只能精确到 16.7ms。再加上线程比运行它们的物理内核多得多的事实，而且你不能指望在不知道自己在做什么的情况下编写具有精确时序的代码。

因此，无论何时编写计时器代码，只要假设您启动的任何计时器都会以 +/- 16 毫秒的精度触发。

于 2015-08-03T18:11:11.190 回答