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这是正确的联锁同步设计吗?

interlocked locking multithreading synchronization c#

5

Dan Bryant · 技术社区 · 16 年前

我有一个取样系统。我在应用程序中有多个客户机线程对这些示例感兴趣,但实际的采样过程只能发生在一个上下文中。它足够快,可以在采样完成之前阻止调用过程,但是足够慢,我不希望多个线程堆积请求。我想出了这个设计(精简到最小的细节):

public class Sample
{
    private static Sample _lastSample;
    private static int _isSampling;

    public static Sample TakeSample(AutomationManager automation)
    {
        //Only start sampling if not already sampling in some other context
        if (Interlocked.CompareExchange(ref _isSampling, 0, 1) == 0)
        {
            try
            {
                Sample sample = new Sample();
                sample.PerformSampling(automation);
                _lastSample = sample;
            }
            finally
            {
                //We're done sampling
                _isSampling = 0;
            }
        }

        return _lastSample;
    }

    private void PerformSampling(AutomationManager automation)
    {
        //Lots of stuff going on that shouldn't be run in more than one context at the same time
    }
}

在我描述的场景中使用这个安全吗?

2 回复 | 直到 16 年前

1

5

Henk Holterman 16 年前

是的,看起来很安全因为 int 这里是原子类型。但我还是会的

private static int _isSampling;

private static object _samplingLock = new object();

使用方法:

lock(_samplingLock)
{
    Sample sample = new Sample();
    sample.PerformSampling(automation);
   _lastSample = sample;
}

注意:我希望速度相当,lock使用内部使用Interlocked的managed Monitor类。

我错过了退后方面,这里是另一个版本:

   if (System.Threading.Monitor.TryEnter(_samplingLock))
   {
     try
     {
         .... // sample stuff
     }
     finally
     {
          System.Threading.Monitor.Exit(_samplingLock);
     }
   }

2

-1

Mike_G 16 年前

我通常会声明一个volatile bool并执行以下操作:

private volatile bool _isBusy;
private static Sample _lastSample;

private Sample DoSomething()
{
     lock(_lastSample)
     {
       if(_isBusy)
          return _lastSample;
       _isBusy = true;
     }

     try
     {
       _lastSample = new sameple//do something
     }
     finally
     {
        lock(_lastSample)
        {
           _isBusy = false;
        }
     }
     return _lastSample;
}