pthread_create() 함수 이용했을 때, thread가 두번 호출되는 것 처럼 나타납니다. 왜 그런것인가요?

#include<stdio.h>

#include<stdlib.h>

#include"pthread.h"

void thread(void vargp);

void main()

{

pthread_t tid;

pthread_create(&tid,NULL,thread,NULL);

//pthread_join(tid,NULL);

printf("End of main\n");

exit(0);

}

void thread(void vargp)

{

printf("thread is created!:%lu\n",pthread_self());

return NULL;

}

결과가 3가지로 나타납니다.

1. End of main

    

2. End of main

   thread is created!:thread is created!:140319790982912

3.  

4. End of main

   thread is created!:140328472020736

   thread is created!:140328472020736