presto-main/src/main/java/io/prestosql/failuredetector/HeartbeatFailureDetector.java/HeartbeatFailureDetector/start
class HeartbeatFailureDetector:    @PostConstruct
    public void start()
    {
        if (isEnabled && started.compareAndSet(false, true)) {
            executor.scheduleWithFixedDelay(new Runnable()
            {
                @Override
                public void run()
                {
                    try {
                        updateMonitoredServices();
                    }
                    catch (Throwable e) {
                        // ignore to avoid getting unscheduled
                        log.warn(e, "Error updating services");
                    }
                }
            }, 0, 5, TimeUnit.SECONDS);
        }
    }