public static bool QueueUserWorkItem(WaitCallback);

public static bool QueueUserWorkItem(WaitCallback, object);

using System;
using System.Collections;
using System.Threading;
namespace ThreadExample
{
 //这是用来保存信息的数据结构，将作为参数被传递
 public class SomeState
 {
 public int Cookie;
 public SomeState(int iCookie)
 {
  Cookie = iCookie;
 }
 }

 public class Alpha
 {
public Hashtable HashCount;
public ManualResetEvent eventX;
public static int iCount = 0;
public static int iMaxCount = 0;

  public Alpha(int MaxCount) 
{
  HashCount = new Hashtable(MaxCount);
  iMaxCount = MaxCount;
}

//线程池里的线程将调用Beta()方法
public void Beta(Object state)
{
 //输出当前线程的hash编码值和Cookie的值
  Console.WriteLine(" {0} {1} :", Thread.CurrentThread.GetHashCode(),((SomeState)state).Cookie);
  Console.WriteLine("HashCount.Count=={0}, Thread.CurrentThread.GetHashCode()=={1}", HashCount.Count, Thread.CurrentThread.GetHashCode());
  lock (HashCount) 
  {
 //如果当前的Hash表中没有当前线程的Hash值，则添加之
 if (!HashCount.ContainsKey(Thread.CurrentThread.GetHashCode()))
   HashCount.Add (Thread.CurrentThread.GetHashCode(), 0);
  HashCount[Thread.CurrentThread.GetHashCode()] = 
   ((int)HashCount[Thread.CurrentThread.GetHashCode()])+1;
 }
   int iX = 2000;
   Thread.Sleep(iX);
   //Interlocked.Increment()操作是一个原子操作，具体请看下面说明
   Interlocked.Increment(ref iCount);

   if (iCount == iMaxCount)
   {
  Console.WriteLine();
 Console.WriteLine("Setting eventX ");
 eventX.Set();
  }
 }
 }
  public class SimplePool
  {
   public static int Main(string[] args)
   {
    Console.WriteLine("Thread Pool Sample:");
    bool W2K = false;
    int MaxCount = 10;//允许线程池中运行最多10个线程
    //新建ManualResetEvent对象并且初始化为无信号状态
    ManualResetEvent eventX = new ManualResetEvent(false);
    Console.WriteLine("Queuing {0} items to Thread Pool", MaxCount);
    Alpha oAlpha = new Alpha(MaxCount); 
    //创建工作项
    //注意初始化oAlpha对象的eventX属性
    oAlpha.eventX = eventX;
    Console.WriteLine("Queue to Thread Pool 0");
    try
    {
     //将工作项装入线程池 
     //这里要用到Windows 2000以上版本才有的API，所以可能出现NotSupportException异常
     ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta), new SomeState(0));
     W2K = true;
    }
    catch (NotSupportedException)
    {
     Console.WriteLine("These API's may fail when called on a non-Windows 2000 system.");
     W2K = false;
    }
    if (W2K)//如果当前系统支持ThreadPool的方法.
    {
     for (int iItem=1;iItem < MaxCount;iItem++)
     {
      //插入队列元素
      Console.WriteLine("Queue to Thread Pool {0}", iItem);
      ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta), new SomeState(iItem));
     }
     Console.WriteLine("Waiting for Thread Pool to drain");
     //等待事件的完成，即线程调用ManualResetEvent.Set()方法
     eventX.WaitOne(Timeout.Infinite,true);
     //WaitOne()方法使调用它的线程等待直到eventX.Set()方法被调用
     Console.WriteLine("Thread Pool has been drained (Event fired)");
     Console.WriteLine();
     Console.WriteLine("Load across threads");
     foreach(object o in oAlpha.HashCount.Keys)
      Console.WriteLine("{0} {1}", o, oAlpha.HashCount[o]);
    }
    Console.ReadLine();
    return 0;
   }
  }
 }
}