Barreira em C

Barreirathread.c

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

#define NUM_THREADS 5
#define MAX_COUNT 100

pthread_barrier_t barrier;
pthread_t threads[NUM_THREADS];

void* dorme_espera(void *arg){
    int retorno, contador, tempo;
    int thread_id = (int) arg;

    while (contador < MAX_COUNT){
        contador +=  thread_id+1;
        usleep(rand() % 100);
    }

    tempo = 999999;
    usleep(tempo);
    printf("Thread %d esperando na barreira apos dormir %d mili segundos. Contador com valor: %d\n", thread_id, tempo, contador);
    retorno = pthread_barrier_wait(&barrier);

    if (retorno != 0 && retorno != PTHREAD_BARRIER_SERIAL_THREAD)
        printf("Erro de espera na barreira na thread %d", thread_id);

	usleep(100000);
	printf("Thread %d terminando\n", thread_id);
}

int main() {
    int i;
	srand(time(NULL));

    if (pthread_barrier_init(&barrier, NULL, NUM_THREADS))
		printf("Impossivel criar barreira");

  	for (i = 0 ; i < NUM_THREADS; i++)
    	if (pthread_create(&threads[i], NULL, dorme_espera, (void*) i))
			printf("Erro na criacao das threads");

    for(i = 0; i < NUM_THREADS; i++)
            if(pthread_join(threads[i], NULL))
                printf("Erro no join");

    usleep(100000);
}