1

我有几个调用方法的线程。它看起来像这样：

public void DoWork(params int[] initialConditions)
{
    //Do a lot of work
}

但是，如果条件变化很快，我会得到很多陈旧的中间结果，因为我无法足够快地完成计算。我知道！我将代码修改为如下所示：

public void DoWork(params int[] initialConditions)
{
    if(Monitor.TryEnter(syncLock)
    {
        //Do a lot of work
        Monitor.Exit(syncLock);
    }
}

现在我不会费心去计算，除非我之前的计算完成了。在快速变化的情况下，我会有点落后，但不会超过我本来应该做的，而且我不会为了过时的结果而浪费我的时间做所有额外的工作。

然而，

一旦情况停止变化，我还是有点过时了，最后一个想调用 DoWork 的线程早已不复存在。有没有办法告诉线程：

if no one is doing work
    do work
else
    wait to do work until after the other thread finishes
but
    if a new thread arrives before you start doing work, leave without doing work.
4

1 回答 1

0

此代码应满足伪代码描述的您的要求：

class Program
{
    static object _workLockObject = new object();
    static volatile int _currentPriority = 0;

    static void Main()
    {
        Task t1 = new Task(() => TryDoWork(1));
        Task t2 = new Task(() => TryDoWork(2));
        Task t3 = new Task(() => TryDoWork(3));

        t1.Start();
        Thread.Sleep(100);
        t2.Start();
        Thread.Sleep(100);
        t3.Start();
        Console.ReadKey();
    }
    public static void TryDoWork(params int[] initialConditions)
    {
        var priotity = Interlocked.Increment(ref _currentPriority);
        while (!Monitor.TryEnter(_workLockObject))// starting to wait when DoWork is available
        {
            if (priotity != _currentPriority) // if the thread has stale parameters
            {
                Console.WriteLine("DoWork skipped " + initialConditions[0]);
                return;// skipping Dowork
            }
            Thread.Sleep(300);// Change the interval according to your needs
        }
        try // beginning of critical section
        {
            if (priotity == _currentPriority) // if the thread has the newest parameters
                DoWork(initialConditions);
        }
        finally
        {
            Monitor.Exit(_workLockObject); // end of critical section
        }
    }
    public static void DoWork(params int[] initialConditions)
    {
        Console.WriteLine("DoWork started " + initialConditions[0]);
        Thread.Sleep(5000);
        Console.WriteLine("DoWork ended " + initialConditions[0]);
    }
}

Interlocked.Increment保证每个线程都有自己的优先级，并且最新的线程具有允许在DoWork可用时执行的优先级。

于 2020-02-06T14:33:55.450 回答