C语言 Pthread互斥锁

C语言 Pthread互斥锁

加减互斥

#include
#include

int num; //临界资源
pthread_mutex_t mutex; //创建互斥锁

void* addfunc(){
    int i=0;
    for(;i<50;i++){
        pthread_mutex_lock(&mutex);
        int tmp = num;
        tmp++;
        usleep(10); //模拟内存写入较慢，被其他线程抢占内存
        num = tmp;
        printf("i'm add,add val is %dn",num);
        pthread_mutex_unlock(&mutex);
    }
    return NULL;
}

void* subfunc(){
    int j=0;
    for(;j<50;j++){
        pthread_mutex_lock(&mutex);
        int tmp = num;
        tmp--;
        num = tmp;
        printf("i'm sub,sub val is %dn",num);
        usleep(5);
        pthread_mutex_unlock(&mutex);
    }
    return NULL;
}

int main(){
    pthread_t add_thread,sub_thread; //声明两个线程ID
    pthread_mutex_init(&mutex,NULL);//互斥锁初始化
    pthread_create(&add_thread, NULL, addfunc, NULL);//创建线程
    pthread_create(&sub_thread, NULL, subfunc, NULL);

    pthread_join(add_thread, NULL);//等待线程结束并回收资源
    pthread_join(sub_thread, NULL);

    pthread_mutex_destroy(&mutex);//销毁互斥锁
    return 0;
}