c++ - pthread_attr_setstacksize 和 pthread_exit

Question

我有一个关于在大约 64Mb RAM 的嵌入式系统中进行 C 并发编程的问题。特别是，我想减少线程使用的默认内存，所以我定义了:

pthread_attr_t attr_test;
size_t stacksize = 0x186A0; // 100Kbyte
pthread_attr_init(&attr_test);
pthread_attr_setdetachstate(&attr_test, PTHREAD_CREATE_DETACHED);    
pthread_attr_setstacksize(&attr_test, stacksize);

因此，当线程启动时，它仅使用 100Kbyte 的虚拟内存。但是当线程结束并调用pthread_exit时，进程使用的虚拟内存会迅速增加!......

为什么？我能做什么？

谢谢!

更新:

主题 ->

void *thread_test(void *arg1) {
    int *param;
    param = (int*)arg1;

    printf("Thread %d start\n", *param);
    pthread_cond_wait(&condition[*param], &mutex[*param]);
    printf("Thread %d stop\n",*param);
    pthread_exit(0);
}

主要 ->

int main(void) {
    pthread_t IDthread[MAX_THREADS];
    int param[MAX_THREADS];
    int pointer;
    int i, keyb;
    void *stkaddr;
    size_t stacksize;

    puts("!!! THREAD TEST !!!");
    printf("Process ID %d\n\n", getpid());

    for(i=0; i<MAX_THREADS; i++)
    {
        pthread_cond_init(&condition[i], NULL);
        pthread_mutex_init(&mutex[i], NULL);
        IDthread[i] = 0;
        param[i] = i;

    }

    stacksize = 0x186A0; // 100Kbyte

    pthread_attr_init(&attr_test);

    pthread_attr_setdetachstate(&attr_test, PTHREAD_CREATE_DETACHED);
    /* setting the size of the stack also */
    pthread_attr_setstacksize(&attr_test, stacksize);

    pointer = 0;


    do {
        keyb = getchar();
        if (keyb == '1')
        {
            if (pointer < MAX_THREADS)
            {
                pthread_create(&IDthread[pointer], &attr_test, thread_test, &param[pointer]);
                sleep(1);
                pointer++;
            }
            else
                puts("MAX Threads Number");
        }

        if (keyb == '2')
        {
            if (pointer != 0)
            {
                pointer--;
                pthread_cond_signal(&condition[pointer]);
                sleep(1);
            }
            else
                puts("0 Thread is running");
        }

    } while (keyb != '0');
    printf("FINE\n");
    return EXIT_SUCCESS;

}

Answer 1

可连接或分离线程存在一个已知问题，引用手册:

Only when a terminated joinable thread has been joined are the last of its resources released back to the system. When a detached thread terminates, its resources are automatically released back to the system

您可以使用以下方法使线程可拆卸:

pthread_attr_setdetachstate(3)