学步园

 using System;<br /> using System.Collections.Generic;<br /> using System.Linq;<br /> using System.Text;<br /> using System.Threading ;<br /> using System.Diagnostics ;<br /> namespace 多线程<br /> {<br /> class Semaphore旗语锁定<br /> {<br /> public static void Main()<br /> {<br /> //旗语锁与互斥锁很像，区别是，旗语可以定义同时由多个线程使用<br /> //是一种计数的互斥锁<br /> //例如，要访问物理的IO端口，且有三个端口可以用，只允许3个线程同时访问IO。<br /> //那么第4个线程则要等前3个中的其中之一释放锁以后，才能抢到锁<br /> int threadCount = 6 ;<br /> int semaphoreCount = 4 ;</p> <p> //初始数与最大请求数都为4<br /> Semaphore semaphore = new Semaphore( semaphoreCount , semaphoreCount );<br /> Thread[] threads = new Thread[ threadCount ] ;</p> <p> for( int i = 0 ; i < threads.Length ; i ++ )<br /> {<br /> threads[i] = new Thread( ThreadMain ) ;<br /> threads[i].Start( semaphore ) ;<br /> }</p> <p> for( int i = 0 ; i < threadCount ; i ++ )<br /> {<br /> //保证所有线程在主线程之前完成<br /> threads[ i ].Join() ;<br /> }</p> <p> Console.WriteLine( "执行完毕" ) ;<br /> Console.ReadLine() ;<br /> }</p> <p> public static void ThreadMain( object o )<br /> {<br /> Semaphore semaphore = o as Semaphore ;<br /> Trace.Assert( semaphore != null , "参数类型不对" ) ;<br /> bool isCompleted = false ;</p> <p> while( !isCompleted )<br /> {<br /> if( semaphore.WaitOne( 600 , false ) )<br /> {<br /> try<br /> {<br /> Console.WriteLine( "线程:{0} 拿到了锁" , Thread.CurrentThread.ManagedThreadId ) ;<br /> // 拿到后睡上2秒<br /> Thread.Sleep( 2000 ) ;<br /> }<br /> finally<br /> {<br /> semaphore.Release() ;<br /> Console.WriteLine( "---线程 {0} 放掉了锁" , Thread.CurrentThread.ManagedThreadId ) ;<br /> isCompleted = true ;<br /> }<br /> }<br /> else<br /> {<br /> Console.WriteLine( "!!!线程{0}等待超时 " , Thread.CurrentThread.ManagedThreadId ) ;<br /> }<br /> }<br /> }<br /> }<br /> }<br />