using System;
     using System.Collections.Generic;
     using System.Linq;
     using System.Text;
     using System.Threading;
       
     namespace MutiThread
     {
         /// <summary>
         /// .net 信号量Semaphore的使用
         /// </summary>
         class Program
         {
             static void Main(string[] args)
             {
                 //初始化4个线程
                 Mythread mythrd1 = new Mythread("Thrd #1");
                 Mythread mythrd2 = new Mythread("Thrd #2");
                 Mythread mythrd3 = new Mythread("Thrd #3");
                 Mythread mythrd4 = new Mythread("Thrd #4");
       
                 //Join()方法阻塞调用线程
                 //达到主线程在4个子线程执行完毕才退出的目的
                 mythrd1.thrd.Join();
                 mythrd2.thrd.Join();
                 mythrd3.thrd.Join();
                 mythrd4.thrd.Join();
       
             }
         }
       
         /// <summary>
         /// 封装线程类
         /// </summary>
         class Mythread
         {
             public Thread thrd;
             //创建一个可授权2个许可证的信号量，且初始值为2
             static Semaphore sem = new Semaphore(2, 2);
       
             public Mythread(string name)
             {
                 thrd = new Thread(this.run);
                 thrd.Name = name;
                 thrd.Start();
             }
       
             void run()
             {
                 Console.WriteLine(thrd.Name + "正在等待一个许可证……");
                 //申请一个许可证
                 sem.WaitOne();
                 Console.WriteLine(thrd.Name + "申请到许可证……");
                 for (int i = 0; i < 4; i++)
                 {
                     Console.WriteLine(thrd.Name + "： " + i);
                     Thread.Sleep(1000);
                 }
                 Console.WriteLine(thrd.Name + " 释放许可证……");
                 //释放许可证
                 sem.Release();
             }
         }
       
     }