Question

在学校我获得了一项任务，即构建一个简单的应用程序来展示线程如何优先处理工作。问题是我开火的线程并没有坚持优先级设置并随机完成（或者看起来如此）。

我主窗口的代码：

namespace ThreadsShowtime
{
    public partial class MainWindow : Window
    {
        private SuperThread _lowest;
        private SuperThread _below;
        private SuperThread _normal;
        private SuperThread _above;
        private SuperThread _highest;

        public MainWindow()
        {
            InitializeComponent();
        }

        private void ButtonClick(object sender, RoutedEventArgs e)
        {
            _lowest = new SuperThread(ThreadPriority.Lowest, elipseLowest, Dispatcher, lowestLbl);
            _below = new SuperThread(ThreadPriority.BelowNormal, elipseBelow, Dispatcher, belowLbl);
            _normal = new SuperThread(ThreadPriority.Normal, elipseNormal, Dispatcher, normalLbl);
            _above = new SuperThread(ThreadPriority.AboveNormal, elipseAbove, Dispatcher, aboveLbl);
            _highest = new SuperThread(ThreadPriority.Highest, elipseHighest, Dispatcher, highestLbl);

            _lowest.Start();
            _below.Start();
            _normal.Start();
            _above.Start();
            _highest.Start();
        }
    }
}

和SuperThread类代码：

namespace ThreadsShowtime
{
    public class SuperThread
    {
        private readonly Stopwatch _stopwatch;
        public readonly Thread Thread;

        public SuperThread(ThreadPriority thp, Shape sh, Dispatcher dispatcher, ContentControl lbl)
        {
            Thread = new Thread(() => DummyMethod(dispatcher, sh, lbl)) {Priority = thp};
            _stopwatch = new Stopwatch();
        }

        public long Elapsed { get; private set; }
        public double ElapsedSeconds => Elapsed / 1000.0;


        private void DummyMethod(Dispatcher dispatcher, Shape sh, ContentControl lbl)
        {
            _stopwatch.Start();
            dispatcher.Invoke(() =>
            {
                sh.Fill = Brushes.GreenYellow;
            }, DispatcherPriority.Normal);    

            for (var idx = 0; idx < 30000; idx++) Console.WriteLine(idx);

            dispatcher.Invoke(() =>
            {
                sh.Fill = Brushes.OrangeRed;
            }, DispatcherPriority.Normal);

            _stopwatch.Stop();
            Elapsed = _stopwatch.ElapsedMilliseconds;

            dispatcher.Invoke(() =>
            {
                lbl.Content = ElapsedSeconds;
            }, DispatcherPriority.ContextIdle);

        }

        public void Start()
        {
            Thread.Start();
        }
    }
}

此应用程序的输出如下所示：

为什么会这样？非常感谢您提供的任何帮助。

Answer 1

由于dispatcher.Invoke()和Console.WriteLine()，您的代码实际上是单线程的。你看到的是排队线程的稍微不可预知的结果。那些队列不是FIFO。

要查看正确的效果，请对一些纯粹受CPU限制的代码进行基准测试，例如Sort（）。确保它们运行＆gt; 200毫秒，较小的运行是没有意义的。

优先级线程未按预期顺序完成工作

1 个答案: