艾伟：C#多线程学习(四) 多线程的自动管理(线程池)

Code

   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;
            }
        }
    }
}

输出的结果

   Thread Pool Sample:
Queuing 10 items to Thread Pool
Queue to Thread Pool 0
Queue to Thread Pool 1
Queue to Thread Pool 2
Queue to Thread Pool 3
Queue to Thread Pool 4
Queue to Thread Pool 5
2 0 :
HashCount.Count==0, Thread.CurrentThread.GetHashCode()==2
Queue to Thread Pool 6
Queue to Thread Pool 7
Queue to Thread Pool 8
Queue to Thread Pool 9
Waiting for Thread Pool to drain
4 1 :
HashCount.Count==1, Thread.CurrentThread.GetHashCode()==4
6 2 :
HashCount.Count==1, Thread.CurrentThread.GetHashCode()==6
7 3 :
HashCount.Count==1, Thread.CurrentThread.GetHashCode()==7
2 4 :
HashCount.Count==1, Thread.CurrentThread.GetHashCode()==2
8 5 :
HashCount.Count==2, Thread.CurrentThread.GetHashCode()==8
9 6 :
HashCount.Count==2, Thread.CurrentThread.GetHashCode()==9
10 7 :
HashCount.Count==2, Thread.CurrentThread.GetHashCode()==10
11 8 :
HashCount.Count==2, Thread.CurrentThread.GetHashCode()==11
4 9 :
HashCount.Count==2, Thread.CurrentThread.GetHashCode()==4

Setting eventX
Thread Pool has been drained (Event fired)

Load across threads
11 1
10 1
9 1
8 1
7 1
6 1
4 2
2 2