#include <string.h>

• memset

#include <stdio.h>

• printf

#include <stdlib.h>

• malloc, free

#include <unistd.h>

• write, usleep

# include <sys/time.h>

• gettimeofday

# include <pthread.h>

• pthread_create, pthread_detach, pthread_join, pthread_mutex_init, pthread_mutex_destroy, pthread_mutex_lock, pthread_mutex_unlock