Question

我最近在C ++中开发了一个用于学习互斥的测试项目。

我创建了两个包装函数：

void Semaphore::semaphore_await(int sem_cluster_id, unsigned short which) //semaphore_p
{
    int zmien_sem;
    sembuf bufor_sem;
    bufor_sem.sem_num = which;
    bufor_sem.sem_op = -1;
    bufor_sem.sem_flg = SEM_UNDO;
    zmien_sem = semop(sem_cluster_id, &bufor_sem, 1);
    if (zmien_sem == -1) {
        printf("Nie moglem zamknac semafora.\n");
        exit(EXIT_FAILURE);
    } else {
//        printf("Semafor S%d zostal zamkniety.\n", which);
    }
}

void Semaphore::semaphore_unlock(int semid, unsigned short which) //semaphore_v
{
    int zmien_sem;
    sembuf bufor_sem;
    bufor_sem.sem_num = which;
    bufor_sem.sem_op = 1;
    bufor_sem.sem_flg = SEM_UNDO;
    zmien_sem = semop(semid, &bufor_sem, 1);
    if (zmien_sem == -1) {
        printf("Nie moglem otworzyc semafora.\n");
        exit(EXIT_FAILURE);
    } else {
//        printf("Semafor S%d zostal otwarty.\n", which);
    }
}

我产生了一些进程来竞争资源，并且有以下机构：

void critical_section(int semid, unsigned short semaphor_number){
    Semaphore::semaphore_await(semid, semaphor_number);
    std::cout<<"I am process:"<<getpid()<<" and I am in critical section!"<<std::endl;
//    sleep(1);
    Semaphore::semaphore_unlock(semid, semaphor_number);
}

问题在于我无法重现互斥现象。一旦单个prcoess进入该部分，它就不会让另一个进程进入该部分，但大多数时候同一个进程执行临界部分...

I am process:32339 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32346 and I am in critical section!
I am process:32341 and I am in critical section!
I am process:32341 and I am in critical section!

在Manjaro或Ubuntu这样的Linux平台下更加令人担忧的是它完美无缺。

OSX semop不会对进程进行排队

0 个答案: