How to stop the thread execution in C++

I created one thread in my main program, thread execution has to stop once main program will terminate. I am using reader.join(); to terminate the thread execution but it is not stopping the execution.

I tried with below-mentioned code, I am using thread.join(); function but it is failed to terminate a thread. & after main program also my thread is kept executing.

  #include <algorithm>
  #include <array>
  #include <atomic>
  #include <mutex>
  #include <queue>
  #include <cstdint>
  #include <thread>
  #include <vector> 

   using namespace std;
   using namespace std::chrono;

   typedef pair<int, Mat> pairImage;

   class PairComp {  
        public:
       bool operator()(const pairImage &n1, const pairImage &n2) const {
        if (n1.first == n2.first) return n1.first > n2.first;
         return n1.first > n2.first;
       }
     };


int main(int argc, char *argv[]) {
mutex mtxQueueInput;                                              
queue<pairImage> queueInput;                                   
int total =0;
atomic<bool> bReading(true);
thread reader([&]() {
    int idxInputImage = 0;
    while (true) {
    Mat img = imread("img_folder/");
        mtxQueueInput.lock();
        queueInput.push(make_pair(idxInputImage++, img));
        if (queueInput.size() >= 100) 
        {
            mtxQueueInput.unlock();
            cout << "[Warning]input queue size is " << queueInput.size();
            // Sleep for a moment
            sleep(2);
        } 
        else {
            mtxQueueInput.unlock();
        }
    }
    bReading.store(false);
});
        while (true) {
            pair<int, Mat> pairIndexImage;
            mtxQueueInput.lock();
            if (queueInput.empty()) {
                mtxQueueInput.unlock();
                if (bReading.load())
                    continue;
                else
                    break;
            } else {
                // Get an image from input queue
                pairIndexImage = queueInput.front();
                queueInput.pop();
            }
            mtxQueueInput.unlock();
    cv::Mat frame = pairIndexImage.second;

         cv::rectangle(frame,cv::Rect{ 100,100,100,100} ,0xff);

     }

        cv::imshow("out_image", frame);
    waitKey(1);

    if (total++ == 200)
        break;

    }
if (reader.joinable()) 
{       
    reader.join();

}
  return 0;

  }