C# Mutex

Mutex

Mutex 类似于C# lock, 区别在于一个Mutex可以在多个进程间使用.也就是说Mutex既是computer-wide又是application-wide.

注意: 获取和释放Mutex大概比lock要多五十倍时间.

调用WaitOne()来获得锁, ReleaseMutex()来解除锁.关闭或者杀死Mutex会自动释放掉锁.和lock一样, Mutex只能从拥有它的线程释放掉.

cross-process Mutex的常见用处是用来确保某个程序只有一个实例在运行.

代码如下:

 

class OneAtATimePlease

{

static void Main()

{

// Naming a Mutex makes it available computer-wide. Use a name that's

// unique to your company and application (e.g., include your URL).

using (var mutex = new Mutex (false, "oreilly.com OneAtATimeDemo"))

{

// Wait a few seconds if contended, in case another instance

// of the program is still in the process of shutting down.

if (!mutex.WaitOne (TimeSpan.FromSeconds (3), false))

{

Console.WriteLine ("Another instance of the app is running. Bye!");

return;

}

RunProgram();

}

}

static void RunProgram()

{

Console.WriteLine ("Running. Press Enter to exit");

Console.ReadLine();

}

}

在Terminal Services下运行时, computer-wide Mutex 只有在同一个terminal server session 中的程序可见, 如果要让它在所有 Terminal Serverces sessions 可见, 则需要在它名字前面加上\.