private long ticklessTimer() {
        // Calculate tickless timer, up to 1 hour
        long tickless = System.currentTimeMillis() + 1000 * 3600;
        for (STimer timer : timers) {
            if (timer.when == -1)
                timer.when = timer.delay + System.currentTimeMillis();
            if (tickless > timer.when)
                tickless = timer.when;
        }
        long timeout = tickless - System.currentTimeMillis();
        if (timeout < 0)
            timeout = 0;
        if (verbose)
            System.out.printf("I: zloop: polling for %d msec\n", timeout);
        return timeout;
    }