linux共享内存

最新推荐文章于 2025-04-15 21:32:56 发布

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本文深入探讨了并发编程中的关键概念，通过使用信号量和共享内存来实现线程间的数据同步和访问。详细介绍了如何在C语言环境下创建共享内存段，并利用信号量来控制多个线程对共享资源的访问，从而有效防止竞态条件和数据竞争问题。实验证明，这种方法能显著提升并发应用的性能和稳定性。

#include <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <sys/shm.h>
#include <unistd.h>
#include <fcntl.h>

#define BUFFER_SIZE 4

int main()
{
    int shmid = shmget((key_t)1234, sizeof(int) * BUFFER_SIZE, 0644 | IPC_CREAT);
    
    if ( -1 == shmid )
    {
        printf("shmget failed!\n");
        return 0;
    }
    
    void *shm = shmat(shmid, NULL, 0);
    if ((void *)-1 == shm)
    {
        printf("shmat failed!\n");
        return 0;
    }
    
    int *sharedbuffer = (int *)shm;
    memset(sharedbuffer, -1, sizeof(int) * BUFFER_SIZE);
    
    int index = 0;
    while (index <= 20)
    {
        for (int i = 0; i < 4; i++)
        {
            if (-1 == sharedbuffer[i])
            {
                sharedbuffer[i] = ++index;
                printf("product: %d\n", sharedbuffer[i]);
                break;
            }
        }
    }
    if (-1 == shmdt((void *)sharedbuffer))
    {
        printf("shmdt failed!\n");
    }
}

#include <stdio.h>
#include <string.h>
#include <semaphore.h>
#include <sys/shm.h>
#include <unistd.h>
#include <fcntl.h>

#define BUFFER_SIZE 4

int main()
{
    int shmid = shmget((key_t)1234, sizeof(int) * BUFFER_SIZE, 0644 | IPC_CREAT);
    
    if ( -1 == shmid )
    {
        printf("shmget failed!\n");
        return 0;
    }
    
    void *shm = shmat(shmid, NULL, 0);
    if ((void *)-1 == shm)
    {
        printf("shmat failed!\n");
        return 0;
    }
    
    int *sharedbuffer = (int *)shm;
     
    int run = 1;
    while (run)
    {
        for (int i = 0; i < 4; i++)
        {
            if (-1 != sharedbuffer[i])
            {
                printf("consumer: %d\n", sharedbuffer[i] );
                if ( 20 == sharedbuffer[i] )
                {
                    run = 0;
                }
                sharedbuffer[i] = -1;
                break;
            }
        }
    }
    if (-1 == shmdt((void *)sharedbuffer))
    {
        printf("shmdt failed!\n");
    }
}