多线程本地图片加载示例【OpenCV】【Pthread】

Pthread barrier的简单使用示例：

C++代码如下：

  

   

    

     

    
    

     

      // ThreadingLoadImages.cpp : 定义控制台应用程序的入口点。
     
    
   

    

     

    
    

     

      //
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      #include "stdafx.h"
     
    
   

    

     

    
    

     

      #include <pthread.h>
     
    
   

    

     

    
    

     

      #include <opencv2/opencv.hpp>
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      #define THREADS 3
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      // Barrier variable
     
    
   

    

     

    
    

     

      pthread_barrier_t barr;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      struct Param
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

      	cv::Mat img;
     
    
   

    

     

    
    

     
	int index;
     
    
   

    

     

    
    

     
	char* file_path;
     
    
   

    

     

    
    

     

      } params[THREADS];
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      void* entry_point(void* arg)
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     

      	Param* p = (Param*)arg;
     
    
   

    

     

    
    

     
	
     
    
   

    

     

    
    

     
	int index = p->index;
     
    
   

    

     

    
    

     
	char* file_path = p->file_path;
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      	p->img = cv::imread(file_path);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	printf("The %d thread is doing job! \n", index);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	// Synchronization point
     
    
   

    

     

    
    

     
	int rc = pthread_barrier_wait(&barr);
     
    
   

    

     

    
    

     
	if (rc != 0 && rc != PTHREAD_BARRIER_SERIAL_THREAD)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		printf("Could not wait on barrier\n");
     
    
   

    

     

    
    

     
		exit(-1);
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      int main()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
	pthread_t thr[THREADS];
     
    
   

    

     

    
    

     
	//pthread_mutex_init(&g_mtx, NULL);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	// Barrier initialization
     
    
   

    

     

    
    

     
	if (pthread_barrier_init(&barr, NULL, THREADS))
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		printf("Could not create a barrier\n");
     
    
   

    

     

    
    

     
		return -1;
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	//int t[THREADS];
     
    
   

    

     

    
    

     

      	params[0].file_path = "../micky.png";
     
    
   

    

     

    
    

     

      	params[1].file_path = "../umbrella.png";
     
    
   

    

     

    
    

     

      	params[2].file_path = "../beard.jpg";
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	for (int i = 0; i < THREADS; ++i)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		//t[i] = i;
     
    
   

    

     

    
    

     

      		params[i].index = i;
     
    
   

    

     

    
    

     
	
     
    
   

    

     

    
    

     
		if (pthread_create(&thr[i], NULL, &entry_point, (void *)&params[i]))
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     
			printf("Could not create thread %d\n", i);
     
    
   

    

     

    
    

     
			return -1;
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	for (int i = 0; i < THREADS; ++i)
     
    
   

    

     

    
    

     

      	{
     
    
   

    

     

    
    

     
		if (pthread_join(thr[i], NULL))
     
    
   

    

     

    
    

     

      		{
     
    
   

    

     

    
    

     
			printf("Could not join thread %d\n", i);
     
    
   

    

     

    
    

     
			return -1;
     
    
   

    

     

    
    

     

      		}
     
    
   

    

     

    
    

     

      	}
     
    
   

    

     

    
    

     
	printf("All threads finish jobs! \n");
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
	for(int i=0; i<THREADS; i++)
     
    
   

    

     

    
    

     

      		cv::imshow(params[i].file_path, params[i].img);
     
    
   

    

     

    
    

     

      	cv::waitKey(0);
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     
    return 0;
     
    
   

    

     

    
    

     

      }
     
    
  
 

相关资料：pthread线程使用小结 

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原文链接：panda1234lee.blog.csdn.net/article/details/53216616