eval.c:9386
void
rb_thread_start_timer()
{
    struct itimerval tval;

    if (!thread_init) return;
    tval.it_interval.tv_sec = 0;
    tval.it_interval.tv_usec = 10000;
    tval.it_value = tval.it_interval;
    setitimer(ITIMER_VIRTUAL, &tval, NULL);
}
