OpenCV/QThread段落

Question

我正在進行生物識別登錄項目，其中人臉識別是其中的一部分。我們正在使用OpenCV 2.4.13。我們有一個Qt的GUI應用程序，它產生一個線程，並通過它的照片來驗證這樣的：

void MainWindow::on_button_test_auth_clicked() 
{ 
    statusLabel->setText("Authenticating..."); 
    statusLabel->repaint(); 

    Mat* takenImage = cam->takePicture(); 

    AuthThread *authThread = new AuthThread(); 
    connect(authThread, SIGNAL(resultReady(const QString&)), this, SLOT(setLabelText(const QString&))); 
    connect(authThread, &AuthThread::finished, authThread, &QObject::deleteLater); 

    authThread->passTakenImage(*takenImage); 
    authThread->start(); 

    delete takenImage; 
} 

AuthThread樣子：

class AuthThread : public QThread 
{ 
    Q_OBJECT 
    void run() Q_DECL_OVERRIDE { 
     Ptr<FaceRecognizer> model = createLBPHFaceRecognizer(4,8,8,8); 

     model->load(Config::getModelFile().toStdString()); 

     int label = -1; 
     double distance = 0.0; 

     model->predict(takenImage, label, distance); 

     QString labelString; 
     QTextStream labelStream(&labelString); 

     double threshold = Config::getThreshold(); 

     if(distance < threshold) { 
      labelStream << "Authenticated as " << label << "! " << QString::number((threshold - distance), 'f', 2) << " under threshold."; 
     } else { 
      labelStream << "Not authenticated! " << QString::number((distance - threshold), 'f', 2) << "over threshold."; 
     } 

     emit resultReady(labelString); 
    } 

public: 
    void passTakenImage(Mat& img) { 
     takenImage = img; 
    } 

private: 
    Mat takenImage; 
signals: 
    void resultReady(const QString &s); 
}; 

這一切工作正常上首次on_button_test_auth_clicked()被調用，但第二次它段錯誤上model->predict(takenImage, label, distance);

我試着運行valgrind，看看究竟是怎麼回事，但我相當新的C++，所以我不能有多大意義的輸出，這是：

==6732== Thread 12 AuthThread: 
==6732== Invalid read of size 8 
==6732== at 0x8C94262: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C9432A: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C95E27: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C94C21: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C8F50F: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C8D724: tbb::internal::allocate_root_with_context_proxy::allocate(unsigned long) const (in /usr/lib/libtbb.so.2) 
==6732== by 0x530D7DA: tbb::interface9::internal::start_for<tbb::blocked_range<int>, cv::calcHist1D_Invoker<float>, tbb::auto_partitioner const>::run(tbb::blocked_range<int> const&, cv::calcHist1D_Invoker<float> const&, tbb::auto_partitioner const&) (in /usr/lib/libopencv_imgproc.so.2.4.13) 
==6732== by 0x531378A: cv::calcHist(cv::Mat const*, int, int const*, cv::_InputArray const&, cv::_OutputArray const&, int, int const*, float const**, bool, bool) (in /usr/lib/libopencv_imgproc.so.2.4.13) 
==6732== by 0x5DABFA5: ??? (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x5DB5899: ??? (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x5DB64DD: cv::LBPH::predict(cv::_InputArray const&, int&, double&) const (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x428940: AuthThread::run() (auththread.h:28) 
==6732== Address 0xfffffffffffffff7 is not stack'd, malloc'd or (recently) free'd 
==6732== 
==6732== 
==6732== Process terminating with default action of signal 11 (SIGSEGV): dumping core 
==6732== Access not within mapped region at address 0xFFFFFFFFFFFFFFF7 
==6732== at 0x8C94262: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C9432A: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C95E27: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C94C21: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C8F50F: ??? (in /usr/lib/libtbb.so.2) 
==6732== by 0x8C8D724: tbb::internal::allocate_root_with_context_proxy::allocate(unsigned long) const (in /usr/lib/libtbb.so.2) 
==6732== by 0x530D7DA: tbb::interface9::internal::start_for<tbb::blocked_range<int>, cv::calcHist1D_Invoker<float>, tbb::auto_partitioner const>::run(tbb::blocked_range<int> const&, cv::calcHist1D_Invoker<float> const&, tbb::auto_partitioner const&) (in /usr/lib/libopencv_imgproc.so.2.4.13) 
==6732== by 0x531378A: cv::calcHist(cv::Mat const*, int, int const*, cv::_InputArray const&, cv::_OutputArray const&, int, int const*, float const**, bool, bool) (in /usr/lib/libopencv_imgproc.so.2.4.13) 
==6732== by 0x5DABFA5: ??? (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x5DB5899: ??? (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x5DB64DD: cv::LBPH::predict(cv::_InputArray const&, int&, double&) const (in /usr/lib/libopencv_contrib.so.2.4.13) 
==6732== by 0x428940: AuthThread::run() (auththread.h:28) 
==6732== If you believe this happened as a result of a stack 
==6732== overflow in your program's main thread (unlikely but 
==6732== possible), you can try to increase the size of the 
==6732== main thread stack using the --main-stacksize= flag. 
==6732== The main thread stack size used in this run was 8388608. 

這似乎表明在libtbb.so，線程構建塊中出現了問題，我認爲這是爲QThread提供動力的。

奇怪的是，當我將AuthThread代碼移動到on_button_test_auth_clicked()時，無論被調用多少次，它都可以正常工作。也許來自舊線程的東西繼續存在，第二次弄亂了東西？

opencv Ptr的工作方式與shared_ptr類似，應該在模型超出範圍後明確清理模型（明確釋放它並沒有幫助）。所有其他的東西都是堆棧分配的，所以他們不應該導致任何內存問題，據我所知。

我試過的另一件事是克隆圖像墊，以防它在需要之前被意外刪除。這也沒有幫助。

爲了增加趣味性，這個確切的代碼在我正在使用的傢伙的計算機上運行良好。任何幫助/提示將非常感激。

Answer 1

要傳遞到一個空對象的引用：

void passTakenImage(Mat& img) { 

之前AuthThread將開始工作，該對象被刪除：

delete takenImage; 

所以，按值傳遞，而不是參考：

void passTakenImage(Mat img) { 

現在，只要AuthThread處於活動狀態，AuthThread就會在img的副本上工作。