gcc/g++でスレッドをスリープさせる

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

void *run(void *p) {
 int t = *(static_cast<int*>(p));
 printf("sleeping %d seconds..\n",t);
 sleep(t); // unit is msec
 pthread_exit(NULL);
}

int main() {

 pthread_t th;
 void* th_result;
 int duration = 2;
 pthread_attr_t attr;
 pthread_attr_init(&attr);
 pthread_attr_setdetachstate(&attr,PTHREAD_CREATE_JOINABLE);
 pthread_create(&th,&attr,run,&duration);
 pthread_attr_destroy(&attr);
 pthread_join(th,&th_result);
 pthread_exit(NULL);

}