如何：对制造者线程和使用者线程进行同步（C# 编程指南）(转自msdn)

转自：http://msdn.microsoft.com/zh-cn/library/yy12yx1f(v=VS.90).aspx

下面的示例演示使用 lock 关键字以及 AutoResetEvent 和 ManualResetEvent 类对主线程和两个辅助线程进行线程同步。有关更多信息，请参见 lock 语句（C# 参考）。

该示例创建两个辅助线程。一个线程生成元素并将它们存储在非线程安全的泛型队列中。有关更多信息，请参见 Queue<T>。另一个线程使用此队列中的项。另外，主线程定期显示队列的内容，以便该队列可由三个线程进行访问。lock 关键字用于同步对队列的访问，以确保队列的状态不会被破坏。

除了只是使用 lock 关键字来防止同时访问以外，还可以用两个事件对象提供进一步的同步。一个事件对象用来通知辅助线程终止，另一个事件对象由制造者线程用来在有新项添加到队列中时通知使用者线程。这两个事件对象封装在一个名为 SyncEvents 的类中。这使事件可以轻松传递给表示制造者线程和使用者线程的对象。SyncEvents 类按如下方式定义：

using System;
using System.Threading;
using System.Collections;
using System.Collections.Generic;

public class SyncEvents
{
    public SyncEvents()
    {

        _newItemEvent = new AutoResetEvent(false);
        _exitThreadEvent = new ManualResetEvent(false);
        _eventArray = new WaitHandle[2];
        _eventArray[0] = _newItemEvent;
        _eventArray[1] = _exitThreadEvent;
    }

    public EventWaitHandle ExitThreadEvent
    {
        get { return _exitThreadEvent; }
    }
    public EventWaitHandle NewItemEvent
    {
        get { return _newItemEvent; }
    }
    public WaitHandle[] EventArray
    {
        get { return _eventArray; }
    }

    private EventWaitHandle _newItemEvent;
    private EventWaitHandle _exitThreadEvent;
    private WaitHandle[] _eventArray;
}
public class Producer
{
    public Producer(Queue<int> q, SyncEvents e)
    {
        _queue = q;
        _syncEvents = e;
    }
    // Producer.ThreadRun
    public void ThreadRun()
    {
        int count = 0;
        Random r = new Random();
        while (!_syncEvents.ExitThreadEvent.WaitOne(0, false))
        {
            lock (((ICollection)_queue).SyncRoot)
            {
                while (_queue.Count < 20)
                {
                    _queue.Enqueue(r.Next(0,100));
                    _syncEvents.NewItemEvent.Set();
                    count++;
                }
            }
        }
        Console.WriteLine("Producer thread: produced {0} items", count);
    }
    private Queue<int> _queue;
    private SyncEvents _syncEvents;
}

public class Consumer
{
    public Consumer(Queue<int> q, SyncEvents e)
    {
        _queue = q;
        _syncEvents = e;
    }
    // Consumer.ThreadRun
    public void ThreadRun()
    {
        int count = 0;
        while (WaitHandle.WaitAny(_syncEvents.EventArray) != 1)
        {
            lock (((ICollection)_queue).SyncRoot)
            {
                int item = _queue.Dequeue();
            }
            count++;
        }
        Console.WriteLine("Consumer Thread: consumed {0} items", count);
    }
    private Queue<int> _queue;
    private SyncEvents _syncEvents;
}

public class ThreadSyncSample
{
    private static void ShowQueueContents(Queue<int> q)
    {
        lock (((ICollection)q).SyncRoot)
        {
            foreach (int item in q)
            {
                Console.Write("{0} ", item);
            }
        }
        Console.WriteLine();
    }

    static void Main()
    {
        Queue<int> queue = new Queue<int>();
        SyncEvents syncEvents = new SyncEvents();

        Console.WriteLine("Configuring worker threads...");
        Producer producer = new Producer(queue, syncEvents);
        Consumer consumer = new Consumer(queue, syncEvents);
        Thread producerThread = new Thread(producer.ThreadRun);
        Thread consumerThread = new Thread(consumer.ThreadRun);

        Console.WriteLine("Launching producer and consumer threads...");       
        producerThread.Start();
        consumerThread.Start();

        for (int i=0; i<4; i++)
        {
            Thread.Sleep(2500);
            ShowQueueContents(queue);
        }

        Console.WriteLine("Signaling threads to terminate...");
        syncEvents.ExitThreadEvent.Set();

        producerThread.Join();
        consumerThread.Join();
    }

}