Mutex 类

同步基元也可用于进程间同步。

有关此类型所有成员的列表，请参阅 Mutex 成员。

System.Object
   System.MarshalByRefObject
      System.Threading.WaitHandle
         System.Threading.Mutex

[Visual Basic]

NotInheritable Public Class Mutex

Inherits WaitHandle

[C#]

public sealed class Mutex : WaitHandle

[C++]

public __gc __sealed class Mutex : public WaitHandle

[JScript]

public class Mutex extends WaitHandle

线程安全

该类型对于多线程操作是安全的。

备注

当两个或更多线程需要同时访问一个共享资源时，系统需要使用同步机制来确保一次只有一个线程使用该资源。Mutex 是同步基元，它只向一个线程授予对共享资源的独占访问权。如果一个线程获取了互斥体，则要获取该互斥体的第二个线程将被挂起，直到第一个线程释放该互斥体。

可以使用 WaitHandle.WaitOne 请求互斥体的所属权。拥有互斥体的线程可以在对 Wait 的重复调用中请求相同的互斥体而不会阻塞其执行。但线程必须调用 ReleaseMutex 方法同样多的次数以释放互斥体的所属权。如果线程在拥有互斥体期间正常终止，则互斥体状态设置为终止，并且下一个等待线程获得所属权。如果没有线程拥有互斥体，则互斥体状态为终止。

示例

[Visual Basic]

' This example shows how a Mutex is used to synchronize access

' to a protected resource. Unlike Monitor, Mutex can be used with

' WaitHandle.WaitAll and WaitAny, and can be passed across

' AppDomain boundaries.

Imports System

Imports System.Threading

Imports Microsoft.VisualBasic

Class Test

' Create a new Mutex. The creating thread does not own the

' Mutex.

Private Shared mut As New Mutex()

Private Const numIterations As Integer = 1

Private Const numThreads As Integer = 3

Shared Sub Main()

' Create the threads that will use the protected resource.

Dim i As Integer

For i = 1 To numThreads

Dim myThread As New Thread(AddressOf MyThreadProc)

myThread.Name = [String].Format("Thread{0}", i)

myThread.Start()

Next i

' The main thread exits, but the application continues to

' run until all foreground threads have exited.

End Sub 'Main

Private Shared Sub MyThreadProc()

Dim i As Integer

For i = 1 To numIterations

UseResource()

Next i

End Sub 'MyThreadProc

' This method represents a resource that must be synchronized

' so that only one thread at a time can enter.

Private Shared Sub UseResource()

' Wait until it is safe to enter.

mut.WaitOne()

Console.WriteLine("{0} has entered protected area", _

Thread.CurrentThread.Name)

' Place code to access non-reentrant resources here.

' Simulate some work

Thread.Sleep(500)

Console.WriteLine("{0} is leaving protected area" & vbCrLf, _

Thread.CurrentThread.Name)

' Release Mutex.

mut.ReleaseMutex()

End Sub 'UseResource

End Class 'MyMainClass

[C#]

// This example shows how a Mutex is used to synchronize access

// to a protected resource. Unlike Monitor, Mutex can be used with

// WaitHandle.WaitAll and WaitAny, and can be passed across

// AppDomain boundaries.

using System;

using System.Threading;

class Test

{

// Create a new Mutex. The creating thread does not own the

// Mutex.

private static Mutex mut = new Mutex();

private const int numIterations = 1;

private const int numThreads = 3;

static void Main()

{

// Create the threads that will use the protected resource.

for(int i = 0; i < numThreads; i++)

{

Thread myThread = new Thread(new ThreadStart(MyThreadProc));

myThread.Name = String.Format("Thread{0}", i + 1);

myThread.Start();

}

// The main thread exits, but the application continues to

// run until all foreground threads have exited.

}

private static void MyThreadProc()

{

for(int i = 0; i < numIterations; i++)

{

UseResource();

}

}

// This method represents a resource that must be synchronized

// so that only one thread at a time can enter.

private static void UseResource()

{

// Wait until it is safe to enter.

mut.WaitOne();

Console.WriteLine("{0} has entered the protected area",

Thread.CurrentThread.Name);

// Place code to access non-reentrant resources here.

// Simulate some work.

Thread.Sleep(500);

Console.WriteLine("{0} is leaving the protected area\r\n",

Thread.CurrentThread.Name);

// Release the Mutex.

mut.ReleaseMutex();

}

}

[C++]

// This example shows how a Mutex is used to synchronize access

// to a protected resource. Unlike Monitor, Mutex can be used with

// WaitHandle.WaitAll and WaitAny, and can be passed across

// AppDomain boundaries.

#using <mscorlib.dll>

using namespace System;

using namespace System::Threading;

const int numIterations = 1;

const int numThreads = 3;

__gc class Test

{

public:

// Create a new Mutex. The creating thread does not own the

// Mutex.

static Mutex* mut = new Mutex();

static void MyThreadProc()

{

for (int i = 0; i < numIterations; i++)

{

UseResource();

}

}

private:

// This method represents a resource that must be synchronized

// so that only one thread at a time can enter.

static void UseResource()

{

//Wait until it is OK to enter.

mut->WaitOne();

Console::WriteLine(S"{0} has entered protected the area",

Thread::CurrentThread->Name

);

// Place code to access non-reentrant resources here.

// Simulate some work.

Thread::Sleep(500);

Console::WriteLine(S"{0} is leaving protected the area\r\n",

Thread::CurrentThread->Name

);

// Release the Mutex.

mut->ReleaseMutex();

}

};

int main()

{

// Create the threads that will use the protected resource.

for (int i = 0; i < numThreads; i++)

{

Thread * myThread = new Thread(

new ThreadStart(0, Test::MyThreadProc)

);

myThread->Name = String::Format(S"Thread {0}", __box(i + 1));

myThread->Start();

}

// The main thread exits, but the application continues to

// run until all foreground threads have exited.

}

[JScript] 没有可用于 JScript 的示例。若要查看 Visual Basic、C# 或 C++ 示例，请单击页左上角的“语言筛选器”按钮 。

要求

命名空间: System.Threading

平台: Windows 98, Windows NT 4.0, Windows ME, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 系列, .NET Framework 精简版

程序集: Mscorlib (在 Mscorlib.dll 中)