System.Threading.ThreadPool vs Semaphore？

Question

示例线程池:

public class Example {
public static void Main() {

    ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc)); //task 1
    ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc)); //task 2
    ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc)); //task 3

    Console.WriteLine("Main thread does some work, then sleeps.");

    Thread.Sleep(1000);

    Console.WriteLine("Main thread exits.");
}
static void ThreadProc(Object stateInfo) {
    Console.WriteLine("Hello from the thread pool.");
}
}

示例信号量:

public class Example
{
private static Semaphore _pool;

private static int _padding;

public static void Main()
{
      _pool = new Semaphore(0, 3);

    // Create and start five numbered threads. 
    //
    for(int i = 1; i <= 5; i++)
    {
        Thread t = new Thread(new ParameterizedThreadStart(Worker));

        t.Start(i);
    }

    Thread.Sleep(500);

     Console.WriteLine("Main thread calls Release(3).");
    _pool.Release(3);

    Console.WriteLine("Main thread exits.");
}

private static void Worker(object num)
{
    Console.WriteLine("Thread {0} begins " +
        "and waits for the semaphore.", num);
    _pool.WaitOne();

    int padding = Interlocked.Add(ref _padding, 100);

    Console.WriteLine("Thread {0} enters the semaphore.", num);

    Thread.Sleep(1000 + padding);

    Console.WriteLine("Thread {0} releases the semaphore.", num);
    Console.WriteLine("Thread {0} previous semaphore count: {1}",
        num, _pool.Release());
}
}

我想它是Semaphore的一些开销,在这个例子中创建5个线程,但是线程池使用内置的"threadpool"(它将使用像backgroundworker这样的现有线程).这是正确的还是更多,使用信号量是否有任何真正的优势,如果你只是想要一个简单的线程池,但速度和性能是一个问题？

Answer 1

你正在比较苹果和奶牛.

ThreadPool允许将Threads用于小任务.它没有任何方便的rendez-vous机制(你的Sleep(1000)是解决这个问题的一个弱解决方案).

信号量是一种同步线程的方法,它们可以是ThreadPool线程.