#include <pthread.h>
#include <unistd.h>
#include <stdio.h>


static pthread_key_t key;


static void *check_key(void *dummy)
{
    /* check the initial key value */
    printf("PID: %d, TID: %lu, init value: %p\n", getpid(),
           pthread_self(), pthread_getspecific(key));
    pthread_setspecific(key, (void *)0xdeadbeef);
    sleep(2);
    return NULL;
}

int main(int argc, char *argv[])
{
    pthread_t pth1, pth2;

    pthread_key_create(&key, NULL);

    pthread_create(&pth1, NULL, check_key, NULL);

    /* let the first thread update its TLS */
    sleep(1);

    if (fork() == 0) {
        /* child */
        pthread_create(&pth2, NULL, check_key, NULL);
        pthread_join(pth2, NULL);
    } else {
        pthread_join(pth1, NULL);
    }

    return 0;
}