问题

1 C++中多个线程共同执行一个实例函数，该函数是在线程的栈空间吗？对于函数中的多线程共享变量又是存储在哪里呢？

example: 在该例子中线程绑定当前对象(this)的实例函数captureVideo, 并将int参数传递过去。但是对于captureVideo中多个线程共享访问的变量，必须通过锁来处理，以防止出现竞态条件

void LoopHTCVPort::KeepCapture()
{
    std::thread t0(std::bind(&LoopHTCVPort::captureVideo, this, 0));
    t0.detach();

    std::thread t1(std::bind(&LoopHTCVPort::captureVideo1, this, 1));
    t1.detach();

    std::thread t2(std::bind(&LoopHTCVPort::captureVideo2, this, 2));
    t2.detach();

    std::thread t3(std::bind(&LoopHTCVPort::captureVideo3, this, 3));
    t3.detach();

    std::thread t4(std::bind(&LoopHTCVPort::captureVideo4, this, 4));
    t4.detach();
}

void LoopHTCVPort::captureVideo(int cameraId)
{
    RobotModel& model = RobotModel::GetGlobalInstance();
    int fps = 20;
    int delay = 1000 / fps;
    tSdkFrameHead frameinfo;
    BYTE* pbyBuffer;
    unsigned char* g_pRgbBuffer;
    int iDisplayFrames = 0;
    int width = 1920;
    int height = 1080;
    std::time_t last = ::GetTimeStamp();
    cv::Mat tempImage;
    while (true)
    {
        int distance = model.Odometer.GetRealValue();
        try
        {
            int index = 0;
            int hCamera;
            for(auto iter = g_hCameraArray.begin(); iter != g_hCameraArray.end(); iter++)
            {
                if (cameraId != index)
                {
                    continue;
                }

                std::time_t now = ::GetTimeStamp();
                cout << "capture last: " << (now - last) << endl;
                last = ::GetTimeStamp();

                g_pRgbBuffer = (unsigned char*) malloc (g_tCapabilityArray[cameraId].sResolutionRange.iHeightMax * g_tCapabilityArray[cameraId].sResolutionRange.iWidthMax * 3);
                hCamera = *iter;
                // 让SDK进入工作模式，开始接收来自相机发送的图像数据。如果当前相机是触发模式，则需要接收到触发帧以后才会更新图像.
                int cplaystatus = CameraPlay(hCamera);
                if(cplaystatus != CAMERA_STATUS_SUCCESS)
                {
                    cout << "CameraPlay faliure! cplaystatus"<< cplaystatus << endl;
                }
                int cgimagestatus = CameraGetImageBuffer(hCamera, &frameinfo, &pbyBuffer, 1000);
                if(cgimagestatus == CAMERA_STATUS_SUCCESS)
		        {
                    int processstatus = CameraImageProcess(hCamera, pbyBuffer, g_pRgbBuffer, &frameinfo);
                    if(processstatus != CAMERA_STATUS_SUCCESS)
                    {
                        cout << "CameraImageProcess error! code: " << processstatus << endl;
                    }
                    tempImage = cv::Mat(cv::Size(frameinfo.iWidth, frameinfo.iHeight), frameinfo.uiMediaType == CAMERA_MEDIA_TYPE_MONO8 ? CV_8UC1 : CV_8UC3, g_pRgbBuffer);
                    //在成功调用CameraGetImageBuffer后，必须调用CameraReleaseImageBuffer来释放获得的buffer, 否则再次调用CameraGetImageBuffer时，程序将被挂起一直阻塞，直到其他线程中调用CameraReleaseImageBuffer来释放了buffer
                    int releasestatus = CameraReleaseImageBuffer(hCamera, pbyBuffer);
                    if(releasestatus != CAMERA_STATUS_SUCCESS)
                    {
                        cout << "CameraReleaseImageBuffer error! code: " << releasestatus << endl;
                    }
                   
                    //test 保存图像到本地
                    // string folderprefix = Setting::ImageStoragePath;
                    // string filename = to_string(iDisplayFrames).append("camera.png");
                    // model.Disk.compressAndSave(matImage, 1, folderprefix, filename);
                    // cout << "image save: " << iDisplayFrames << endl;
                    // ++iDisplayFrames;                    
                    funcallback(cameraId, tempImage);
		        } else
                {
                    cout << "CameraGetImageBuffer occur error! code: " << cgimagestatus << endl;
                }
                // 需要释放内存，否则内存会一直增加
                free(g_pRgbBuffer);
                index ++;
                break;
            }
        }
        catch(std::exception e)
        {
            cout << "Detection camera capture pictures error! " << e.what() << endl;
            releaseHTCamera();
            free(g_pRgbBuffer);
        }
        //usleep(delay * 1000);
    }
}

2 在C++中，多个线程共同执行一个实例函数和共同执行一个静态函数有一些关键的区别。以下是一些主要的区别？