#include <stdio.h>

#include <pthread.h>

pthread_key_t key;

pthread_once_t ponce = PTHREAD_ONCE_INIT;

void ronce(){

        printf("%s\n", "ronce");

}

void *thread1(){

        pthread_setspecific(key, "thread1");

        printf("%s\n", pthread_getspecific(key));

        pthread_once(&ponce, ronce);

}

void *thread2(){

        pthread_setspecific(key, "thread2");

        printf("%s\n", pthread_getspecific(key));

        pthread_once(&ponce, ronce);

}

int main(){

        pthread_key_create(&key, NULL);

        pthread_t tid1, tid2;

        pthread_create(&tid1, NULL, thread1, NULL);

        pthread_create(&tid2, NULL, thread2, NULL);

        pthread_join(tid1, NULL);

        pthread_join(tid2, NULL);

        pthread_key_delete(key);

}