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)