oqp.c

#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/resource.h>
#include <unistd.h>

static volatile int running = 1;

static void sig_handler(int sig __attribute__((unused)))
{
    printf("[%p] stop\n", pthread_self());
    running = 0;
}

static void *oqp(void *ptr __attribute__((unused)))
{
    int policy;
    struct sched_param sched_param;
    int retcode;

    retcode = pthread_getschedparam(pthread_self(), &policy, &sched_param);
    if (retcode != 0) {
        perror("pthread_getschedparam");
    } else {
        printf("[%p] policy=%d sched_prio=%d\n", pthread_self(), policy, sched_param.sched_priority);
    }

    while (1) {
        if (running == 0) {
            break;
        }
    }

    return NULL;
}

int main(int argc, char *argv[])
{
    int nb_oqp = 4;
    const id_t current_process = 0;
    int prio;
    int retcode;
    pthread_t *thread_ids;

    if (argc > 1) {
        nb_oqp = atoi(argv[1]);
    }
    if (nb_oqp < 1 || nb_oqp > (int)sysconf(_SC_NPROCESSORS_ONLN)) {
        fprintf(stderr, "Error: nb_oqp must be between 1 and %ld\n", sysconf(_SC_NPROCESSORS_ONLN));
        exit(EXIT_FAILURE);
    }

    prio = getpriority(PRIO_PROCESS, current_process);
    printf("[%p] old priority: %d\n", pthread_self(), prio);

    retcode = setpriority(PRIO_PROCESS, current_process, PRIO_DARWIN_BG);
    if (retcode != 0) {
        perror("setpriority");
    }

    prio = getpriority(PRIO_PROCESS, current_process);
    printf("[%p] new priority: %d\n", pthread_self(), prio);

    signal(SIGINT, &sig_handler);
    signal(SIGQUIT, &sig_handler);
    signal(SIGTERM, &sig_handler);
    signal(SIGHUP, &sig_handler);

    thread_ids = (pthread_t *)malloc(sizeof(pthread_t) * (nb_oqp - 1));

    for (int i = 0; i < nb_oqp - 1; ++i) {
        retcode = pthread_create(&thread_ids[i], NULL, &oqp, NULL);
        if (retcode != 0) {
            perror("pthread_create");
        } else {
            printf("[%p] new thread %d: %p\n", pthread_self(), i, thread_ids[i]);
        }
    }

    oqp(NULL);

    for (int i = 0; i < nb_oqp - 1; ++i) {
        retcode = pthread_join(thread_ids[i], NULL);
        if (retcode != 0) {
            perror("pthread_join");
        }
        printf("[%p] join thread %p\n", pthread_self(), thread_ids[i]);
    }

    free(thread_ids);

    printf("[%p] exit\n", pthread_self());

    return 0;
}