多线程c#之间的控制/同步变量

Question

我在使用以下代码时遇到了一些时间问题。基本上我有“recordingOn”，当为真时，假设开始将帧写入文件。在下面的程序中，当我有时执行 Stop_Button_Click 时，“writer1.Write(frame1);”出现异常行，这很可能是因为它是在我已经完成 dispose() 之后才这样做的。我如何同步这个？谢谢！

private bool recordingOn = false;

private void ConnectCameras_Button_Click(object sender, EventArgs e)
{
    if (!captureInProgress) //Start cameras streaming
    {
        camera1Capture.ImageGrabbed += ProcessFrame;
        camera1Capture.Start();
    }
    else //Stop cameras streaming
    {
        camera1Capture.Stop();
        imageBox1.Image = null;
        camera1Capture.ImageGrabbed -= ProcessFrame;
    }
    captureInProgress = !captureInProgress;
}

private void ProcessFrame(object sender, EventArgs arg)
{
    camera1Capture.Retrieve(frame1);
    imageBox1.Image = frame1;

    if (recordingOn)
    {
        try
        {
            writer1.Write(frame1);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
}

private void Stop_Button_Click(object sender, EventArgs e)
{
    // Doing other stuff...
    recordingOn = false;
    writer1.Dispose();      
}

Answer 1

基本问题是跨多个线程的共享变量。请使用lock 控制对共享变量的访问。 Lock 确保一次只有一个线程可以访问一个变量。

private bool recordingOn = false;
private static object _lock = new Object();

private void ConnectCameras_Button_Click(object sender, EventArgs e)
{
    if (!captureInProgress) //Start cameras streaming
    {
        camera1Capture.ImageGrabbed += ProcessFrame;
        camera1Capture.Start();
    }
    else //Stop cameras streaming
    {
        camera1Capture.Stop();
        imageBox1.Image = null;
        camera1Capture.ImageGrabbed -= ProcessFrame;
    }
    captureInProgress = !captureInProgress;
}

private void ProcessFrame(object sender, EventArgs arg)
{
    camera1Capture.Retrieve(frame1);
    imageBox1.Image = frame1;
    lock (_lock)
    {
    if (recordingOn)
    {
        try
        {
            writer1.Write(frame1);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message);
        }
    }
    }
}

private void Stop_Button_Click(object sender, EventArgs e)
{
    // Doing other stuff...
    lock (_lock)
    {
      recordingOn = false;
      writer1.Dispose();   
    }

}