如何控制好多个线程相互之间的联系，不产生冲突和重复，这需要用到互斥对象，即：System.Threading 命名空间中的 Mutex 类。
我们可以把Mutex看作一个出租车，乘客看作线程。乘客首先等车，然后上车，最后下车。当一个乘客在车上时，其他乘客就只有等他下车以后才可以上车。而线程与Mutex对象的关系也正是如此，线程使用Mutex.WaitOne()方法等待Mutex对象被释放，如果它等待的Mutex对象被释放了，它就自动拥有这个对象，直到它调用Mutex.ReleaseMutex()方法释放这个对象，而在此期间，其他想要获取这个Mutex对象的线程都只有等待。
下面这个例子使用了Mutex对象来同步四个线程，主线程等待四个线程的结束，而这四个线程的运行又是与两个Mutex对象相关联的。
其中还用到AutoResetEvent类的对象，可以把它理解为一个信号灯。这里用它的有信号状态来表示一个线程的结束。// AutoResetEvent.Set()方法设置它为有信号状态// AutoResetEvent.Reset()方法设置它为无信号状态Mutex 类的程序示例：
using System; using System.Threading; namespace ThreadExample{ public class MutexSample { static Mutex gM1; static Mutex gM2; const int ITERS = 100 ; static AutoResetEvent Event1 = new AutoResetEvent( false ); static AutoResetEvent Event2 = new AutoResetEvent( false ); static AutoResetEvent Event3 = new AutoResetEvent( false ); static AutoResetEvent Event4 = new AutoResetEvent( false ); public static void Main(String[] args) { Console.WriteLine( " Mutex Sample 
" ); // 创建一个Mutex对象，并且命名为MyMutex gM1 = new Mutex( true , " MyMutex " ); // 创建一个未命名的Mutex 对象. gM2 = new Mutex( true ); Console.WriteLine( " - Main Owns gM1 and gM2 " ); AutoResetEvent[] evs = new AutoResetEvent[ 4 ]; evs[ 0 ] = Event1; // 为后面的线程t1,t2,t3,t4定义AutoResetEvent对象 evs[ 1 ] = Event2; evs[ 2 ] = Event3; evs[ 3 ] = Event4; MutexSample tm = new MutexSample( ); Thread t1 = new Thread( new ThreadStart(tm.t1Start)); Thread t2 = new Thread( new ThreadStart(tm.t2Start)); Thread t3 = new Thread( new ThreadStart(tm.t3Start)); Thread t4 = new Thread( new ThreadStart(tm.t4Start)); t1.Start( ); // 使用Mutex.WaitAll()方法等待一个Mutex数组中的对象全部被释放 t2.Start( ); // 使用Mutex.WaitOne()方法等待gM1的释放 t3.Start( ); // 使用Mutex.WaitAny()方法等待一个Mutex数组中任意一个对象被释放 t4.Start( ); // 使用Mutex.WaitOne()方法等待gM2的释放 Thread.Sleep( 2000 ); Console.WriteLine( " - Main releases gM1 " ); gM1.ReleaseMutex( ); // 线程t2,t3结束条件满足 Thread.Sleep( 1000 ); Console.WriteLine( " - Main releases gM2 " ); gM2.ReleaseMutex( ); // 线程t1,t4结束条件满足 // 等待所有四个线程结束 WaitHandle.WaitAll(evs); Console.WriteLine( " Mutex Sample " ); Console.ReadLine(); } public void t1Start( ) { Console.WriteLine( " t1Start started, Mutex.WaitAll(Mutex[]) " ); Mutex[] gMs = new Mutex[ 2 ]; gMs[ 0 ] = gM1; // 创建一个Mutex数组作为Mutex.WaitAll()方法的参数 gMs[ 1 ] = gM2; Mutex.WaitAll(gMs); // 等待gM1和gM2都被释放 Thread.Sleep( 2000 ); Console.WriteLine( " t1Start finished, Mutex.WaitAll(Mutex[]) satisfied " ); Event1.Set( ); // 线程结束，将Event1设置为有信号状态 } public void t2Start( ) { Console.WriteLine( " t2Start started, gM1.WaitOne( ) " ); gM1.WaitOne( ); // 等待gM1的释放 Console.WriteLine( " t2Start finished, gM1.WaitOne( ) satisfied " ); Event2.Set( ); // 线程结束，将Event2设置为有信号状态 } public void t3Start( ) { Console.WriteLine( " t3Start started, Mutex.WaitAny(Mutex[]) " ); Mutex[] gMs = new Mutex[ 2 ]; gMs[ 0 ] = gM1; // 创建一个Mutex数组作为Mutex.WaitAny()方法的参数 gMs[ 1 ] = gM2; Mutex.WaitAny(gMs); // 等待数组中任意一个Mutex对象被释放 Console.WriteLine( " t3Start finished, Mutex.WaitAny(Mutex[]) " ); Event3.Set( ); // 线程结束，将Event3设置为有信号状态 } public void t4Start( ) { Console.WriteLine( " t4Start started, gM2.WaitOne( ) " ); gM2.WaitOne( ); // 等待gM2被释放 Console.WriteLine( " t4Start finished, gM2.WaitOne( ) " ); Event4.Set( ); // 线程结束，将Event4设置为有信号状态 } }}
" ); // 创建一个Mutex对象，并且命名为MyMutex gM1 = new Mutex( true , " MyMutex " ); // 创建一个未命名的Mutex 对象. gM2 = new Mutex( true ); Console.WriteLine( " - Main Owns gM1 and gM2 " ); AutoResetEvent[] evs = new AutoResetEvent[ 4 ]; evs[ 0 ] = Event1; // 为后面的线程t1,t2,t3,t4定义AutoResetEvent对象 evs[ 1 ] = Event2; evs[ 2 ] = Event3; evs[ 3 ] = Event4; MutexSample tm = new MutexSample( ); Thread t1 = new Thread( new ThreadStart(tm.t1Start)); Thread t2 = new Thread( new ThreadStart(tm.t2Start)); Thread t3 = new Thread( new ThreadStart(tm.t3Start)); Thread t4 = new Thread( new ThreadStart(tm.t4Start)); t1.Start( ); // 使用Mutex.WaitAll()方法等待一个Mutex数组中的对象全部被释放 t2.Start( ); // 使用Mutex.WaitOne()方法等待gM1的释放 t3.Start( ); // 使用Mutex.WaitAny()方法等待一个Mutex数组中任意一个对象被释放 t4.Start( ); // 使用Mutex.WaitOne()方法等待gM2的释放 Thread.Sleep( 2000 ); Console.WriteLine( " - Main releases gM1 " ); gM1.ReleaseMutex( ); // 线程t2,t3结束条件满足 Thread.Sleep( 1000 ); Console.WriteLine( " - Main releases gM2 " ); gM2.ReleaseMutex( ); // 线程t1,t4结束条件满足 // 等待所有四个线程结束 WaitHandle.WaitAll(evs); Console.WriteLine( " Mutex Sample " ); Console.ReadLine(); } public void t1Start( ) { Console.WriteLine( " t1Start started, Mutex.WaitAll(Mutex[]) " ); Mutex[] gMs = new Mutex[ 2 ]; gMs[ 0 ] = gM1; // 创建一个Mutex数组作为Mutex.WaitAll()方法的参数 gMs[ 1 ] = gM2; Mutex.WaitAll(gMs); // 等待gM1和gM2都被释放 Thread.Sleep( 2000 ); Console.WriteLine( " t1Start finished, Mutex.WaitAll(Mutex[]) satisfied " ); Event1.Set( ); // 线程结束，将Event1设置为有信号状态 } public void t2Start( ) { Console.WriteLine( " t2Start started, gM1.WaitOne( ) " ); gM1.WaitOne( ); // 等待gM1的释放 Console.WriteLine( " t2Start finished, gM1.WaitOne( ) satisfied " ); Event2.Set( ); // 线程结束，将Event2设置为有信号状态 } public void t3Start( ) { Console.WriteLine( " t3Start started, Mutex.WaitAny(Mutex[]) " ); Mutex[] gMs = new Mutex[ 2 ]; gMs[ 0 ] = gM1; // 创建一个Mutex数组作为Mutex.WaitAny()方法的参数 gMs[ 1 ] = gM2; Mutex.WaitAny(gMs); // 等待数组中任意一个Mutex对象被释放 Console.WriteLine( " t3Start finished, Mutex.WaitAny(Mutex[]) " ); Event3.Set( ); // 线程结束，将Event3设置为有信号状态 } public void t4Start( ) { Console.WriteLine( " t4Start started, gM2.WaitOne( ) " ); gM2.WaitOne( ); // 等待gM2被释放 Console.WriteLine( " t4Start finished, gM2.WaitOne( ) " ); Event4.Set( ); // 线程结束，将Event4设置为有信号状态 } }} 程序的输出结果：
Mutex Sample - Main Owns gM1 and gM2 t1Start started, Mutex.WaitAll(Mutex[]) t2Start started, gM1.WaitOne( ) t3Start started, Mutex.WaitAny(Mutex[]) t4Start started, gM2.WaitOne( ) - Main releases gM1 t2Start finished, gM1.WaitOne( ) satisfied t3Start finished, Mutex.WaitAny(Mutex[]) - Main releases gM2 t1Start finished, Mutex.WaitAll(Mutex[]) satisfied t4Start finished, gM2.WaitOne( ) Mutex Sample
- Main Owns gM1 and gM2 t1Start started, Mutex.WaitAll(Mutex[]) t2Start started, gM1.WaitOne( ) t3Start started, Mutex.WaitAny(Mutex[]) t4Start started, gM2.WaitOne( ) - Main releases gM1 t2Start finished, gM1.WaitOne( ) satisfied t3Start finished, Mutex.WaitAny(Mutex[]) - Main releases gM2 t1Start finished, Mutex.WaitAll(Mutex[]) satisfied t4Start finished, gM2.WaitOne( ) Mutex Sample 从执行结果可以很清楚地看到，线程t2,t3的运行是以gM1的释放为条件的，而t4在gM2释放后开始执行，t1则在gM1和gM2都被释放了之后才执行。Main()函数最后，使用WaitHandle等待所有的AutoResetEvent对象的信号，这些对象的信号代表相应线程的结束。
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