using System;using System.Collections.Generic;using System.Linq;using System.Text;using System.IO;using System.Diagnostics;using System.Threading;using System.ComponentModel;using System.Collections;using System.Net;using System.Runtime.Serialization;using System.Xml;using System.Globalization;using System.Text.RegularExpressions;using System.Data;using System.Data.SqlClient;namespace ConsoleApp{ /// <summary> /// 線程控制隊列 /// Semaphore類 /// </summary> class Program {  static Semaphore semaphore;  static void Main(string[] args)  {   semaphore = new Semaphore(0, 2);   Thread thread;   for (int i = 0; i <= 5; i++)   {    thread = new Thread(new ParameterizedThreadStart(Run));    thread.Start("thread_"+i.ToString());   }   semaphore.Release(2);   Console.ReadLine();  }  static void Run(object obj)  {   semaphore.WaitOne();   Console.WriteLine("thread " + obj.ToString() + " into the method");   System.Threading.Thread.Sleep(5000);      Console.WriteLine("_thread " + obj.ToString() + " leave the method");   semaphore.Release();  } }}