使工作线程等待任务的最有效CPU方法是什么？

Question

在我当前的C#/ NET 3.5应用程序中,我有一个任务队列(线程安全),我有5个工作线程,必须不断查找队列中的任务.如果任务可用,任何一个工作人员都会使任务出列并采取必要的操作.

我的工作线程类如下:

public class WorkerThread
{
    //ConcurrentQueue is my implementation of thread safe queue
    //Essentially just a wrapper around Queue<T> with synchronization locks
    readonly ConcurrentQueue<CheckPrimeTask> mQ; 
    readonly Thread mWorker;
    bool mStop;

    public WorkerThread (ConcurrentQueue<CheckPrimeTask> aQ) {
        mQ = aQ;
        mWorker = new Thread (Work) {IsBackground = true};
        mStop = false;
    }

    private void Work () {
        while (!mStop) {
            if (mQ.Count == 0) {
                Thread.Sleep (0);
                continue;
            }

            var task = mQ.Dequeue ();
            //Someone else might have been lucky in stealing
            //the task by the time we dequeued it!!
            if (task == null) 
                continue;

            task.IsPrime = IsPrime (task.Number);
            task.ExecutedBy = Thread.CurrentThread.ManagedThreadId;
            //Ask the threadpool to execute the task callback to 
            //notify completion
            ThreadPool.QueueUserWorkItem (task.CallBack, task);
        }
    }

    private bool IsPrime (int number) {
        int limit = Convert.ToInt32 (Math.Sqrt (number));
        for (int i = 2; i <= limit; i++) {
            if (number % i == 0)
                return false;
        }

        return true;
    }

    public void Start () {
        mStop = false;
        mWorker.Start ();
    }

    public void Stop () {
        mStop = true;
    }
}

问题是当队列为空时,它会消耗太多的CPU(接近98%).我尝试使用AutoResetEvent来通知工作人员队列已被更改.所以他们有效地等待该信号设定.它已经将CPU降至接近0%,但我不完全确定这是否是最好的方法.你能建议一个更好的方法来保持线程空闲而不损害CPU使用率吗？

Answer 1

查看BlockingQueue的这种实现.如果队列为空,则使用Monitor.Wait()将线程置于休眠状态.添加项目时,它使用Monitor.Pulse()来唤醒正在空队列中休眠的线程.

另一种技术是使用信号量.每次将项添加到队列时,请调用Release().如果需要队列中的项目,请调用WaitOne().