malloc() fails in QtConcurrent::run()

imageworker.cpp

    QImage createImageAsync(QString path)
    {
        QImageReader reader(path);
        if(!reader.canRead())
           return QImage();
        // QImage processing sometimes fails
        QImage src;
        int count = 0;
        do {
            //src = QImage::fromData(bytes, QFileInfo(path.toLower()).suffix().toUtf8());
            src = reader.read();
            if(!src.isNull())
                break;
            if(src.isNull() && count++ < 1000) {
                QThread::currentThread()->usleep(1000);
                continue;
            }
            return QImage();
        } while(1);
        return src;
    }