#define RES_SIGNAL SIGUSR2
int gs_signal_createtimer(void)
{
    struct sigevent sev;

    /*
     * Set up per thread timer.
     * Upon timeout, a SIGUSR2 will be dilivered to current thread itself.
     * The signal handler can check sival_ptr for the reason. We don't want
     * to use SIGEV_THREAD callback method, because it needs certain environment
     * set up to work correctly. Meanwhile, it creates a new thread for the
     * callback, which is inefficiently.
     */
    sev.sigev_notify = SIGEV_SIGNAL | SIGEV_THREAD_ID;
    sev.sigev_signo = RES_SIGNAL;
    sev.sigev_value.sival_ptr = (void*)(SIGALRM + gs_thread_self());
    sev._sigev_un._tid = syscall(SYS_gettid);

    if (timer_create(CLOCK_REALTIME, &sev, &t_thrd.utils_cxt.sigTimerId) == -1) {
        ereport(FATAL, (errmsg("failed to create timer for thread")));
        return -1;
    }

    return 0;
}