在ASP.NET C＃code互斥的释放问题 [英] Mutex release issues in ASP.NET C# code

问题描述

我不完全知道如何解决这个问题。我有一个声明为这样一个互斥体：

I'm not exactly sure how to address this issue. I have a mutex that is declared as such:

public class MyNamedLock
{
    private Mutex mtx;
    private string _strLkName;

    public MyNamedLock(string strLockName)
    {
        _strLkName = strLockName;
        //...

        mtx = new Mutex(false, _strLkName, out bCreatedNew, mSec);
    }

    public bool enterLockWithTimeout(int nmsWait = 30 * 1000)
    {
        _nmsWaitLock = nmsWait;

        //Wait
        return mtx.WaitOne(nmsWait);
    }

    public void leaveLock()
    {
        _nmsWaitLock = 0;

        //Release it
        mtx.ReleaseMutex();
    }
}

然后，它在ASP.NET页面被用作这样的：

Then it is used in an ASP.NET page as such:

public class MyClass
{
    private MyNamedLock gl;

    public MyClass()
    {
        gl = new MyNamedLock("lock name");

    }


    public void funct()
    {
        try
        {
            //Enter lock
            if (gl.enterLockWithTimeout())
            {
                //Do work
            }
            else
                throw new Exception("Failed to enter lock");
        }
        finally
        {
            //Leave lock
            gl.leaveLock();
        }
    }
}

这code没有给我任何麻烦，在我的开发环境，但生产它有时会引发此异常：

This code doesn't give me any trouble in my dev environment but in the production it sometimes throws this exception:

对象同步方法是从一个同步的块被称为
  的code。

Object synchronization method was called from an unsynchronized block of code.

描述是有点模糊，但只是在做我发现异常是在 mtx.ReleaseMutex（）提出的痕迹; 部分。是什么意思，如何解决？

The description is kinda vague, but just doing the trace I found out that the exception is raised at the mtx.ReleaseMutex(); part. What does it mean and how to fix it?

推荐答案

您对您的类中的一些问题，并在你的方式使用它。

You have some issues on your class, and on the way you use it.

1. 您必须释放只有当你有previous锁定互斥（这是你的错误）


2. 您需要关闭并处置您打开互斥


3. 同样是更好的只是你要使用它，而不是当你创建你上课之前创建它 MyClass的。

1. You must release the mutex only if you have previous locked (and this is your error)
2. You need to Close and Dispose your opened mutex
3. Also is better to create it just before you going to use it and not when you create you class MyClass.

所以我建议在第一次看改变你的类：

So I suggest at first look to change your class as:

public class MyNamedLock
{
    private Mutex mtx = null;
    private string _strLkName;

    // to know if finally we get lock
    bool cNeedToBeRelease = false;

    public MyNamedLock(string strLockName)
    {
        _strLkName = strLockName;
        //...

        mtx = new Mutex(false, _strLkName, out bCreatedNew, mSec);
    }

    public bool enterLockWithTimeout(int nmsWait = 30 * 1000)
    {
        _nmsWaitLock = nmsWait;
        bool cLock = false;
        try
        {
            cLock = mtx.WaitOne(nmsWait, false);
            cNeedToBeRelease = cLock;    
        }
        catch (AbandonedMutexException)
        {
            // http://stackoverflow.com/questions/654166/wanted-cross-process-synch-that-doesnt-suffer-from-abandonedmutexexception
            // http://msdn.microsoft.com/en-us/library/system.threading.abandonedmutexexception.aspx
            cNeedToBeRelease = true;
        }
        catch (Exception x)
        {
            // log the error
            Debug.Fail("Check the reason of fail:" + x.ToString());
        }            

        return cLock;        
    }

    public void leaveLock()
    {
        _nmsWaitLock = 0;

        if (mtx != null)
        {
            if (cNeedToBeRelease)
            {
                try
                {
                    mtx.ReleaseMutex();
                    cNeedToBeRelease = false;    
                }
                catch (Exception x)
                {
                    Debug.Fail("Check the reason of fail:" + x.ToString());
                }
            }

            mtx.Close();
            mtx.Dispose();
            mtx = null;
        }
    }
}

这必须调用类的方式：

public class MyClass
{
    public MyClass()
    {
    }


    public void funct()
    {
        var gl = new MyNamedLock("lock name");
        try
        {
            //Enter lock
            if (gl.enterLockWithTimeout())
            {
                //Do work
            }
            else
                throw new Exception("Failed to enter lock");
        }
        finally
        {
            //Leave lock
            gl.leaveLock();
        }
    }
}

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