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.