进程锁 process mutex ？？

最新推荐文章于 2023-01-04 12:49:10 发布

gorunbu

最新推荐文章于 2023-01-04 12:49:10 发布

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分类专栏： linux 文章标签： mutex

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本文探讨了并发编程中的互斥锁机制，详细介绍了如何使用共享内存区域实现进程间的互斥操作，通过创建线程并进行锁操作演示了并发环境下数据同步的基本原理。

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#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <string.h>
#include <stdlib.h>
#include <pthread.h>
#include <sys/mman.h>


static pthread_mutex_t *mutex;

static volatile int i;

void* Thread_Process(void* arg)
{

    printf("thread 2 id=%lu   i=%d\n", pthread_self(), i);
    i+=100;
    printf("Process 2 lock...\n");
    pthread_mutex_lock(mutex);
    printf("Process 2 locked ok\n");
    sleep(1);
    printf("i=%d\n",i);
    printf("Process 2 unlock\n");
    pthread_mutex_unlock(mutex);
}



int main(int argc, char* argv[])
{

    pthread_t pid;
    pthread_mutexattr_t attr;

    mutex=mmap(NULL,sizeof(pthread_mutex_t),PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANON,-1,0);
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_setpshared(&attr,PTHREAD_PROCESS_SHARED);

    if(0!=pthread_create(&pid,NULL,Thread_Process,NULL)){
        perror("pthread_cerate");
    }
    i=100;
    printf("Process 1 lock...\n");
    pthread_mutex_lock(mutex);
    printf("Process 1 locked ok\n");
    sleep(1);
    printf("thread 1 id=%lu   i=%d\n", pthread_self(), i);
    printf("Process 1 unlock\n");
    pthread_mutex_unlock(mutex);
}

//share pthread mutex for process
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include <pthread.h>

int main(int argc, char* argv[])
{
    static pthread_mutex_t *mutex;
    int i;
    pthread_mutexattr_t attr;

    mutex=mmap(NULL,sizeof(pthread_mutex_t),PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANON,-1,0);
    pthread_mutexattr_init(&attr);
    pthread_mutexattr_setpshared(&attr,PTHREAD_PROCESS_SHARED);

    pthread_mutex_init(mutex,&attr);
    int *sharedPtr=mmap(NULL,101,PROT_READ|PROT_WRITE,MAP_SHARED|MAP_ANON,-1,0);
    sharedPtr[0]=9;
    pid_t pid=fork();
    if(pid==0){
        printf("Process 1 pid=%d     lock...\n", getpid() );
        pthread_mutex_lock(mutex);
        printf("Process 1 locked ok  sharedPtr[0]=%d\n", sharedPtr[0]);
        sharedPtr[0] += 10;
        printf("Process 1 pid=%d     unlock\n", getpid() );
        pthread_mutex_unlock(mutex);
    }else{
            printf("Process 2 pid=%d     lock...\n", getpid() );
            pthread_mutex_lock(mutex);
            printf("Process 2 lock ok!   sharedPtr[0]=%d\n",  sharedPtr[0]);
            sharedPtr[0] += 100;
            pthread_mutex_unlock(mutex);
            printf("Process 2 pid=%d     unlock ok\n", getpid() );
    }

    wait(NULL);
    printf("pid=%d     sharedPtr[0]=%d\n", getpid(), sharedPtr[0] );
    munmap(sharedPtr,101);
    return 0;
}