presto-main/src/main/java/io/prestosql/metadata/DiscoveryNodeManager.java/DiscoveryNodeManager/startPollingNodeStates
class DiscoveryNodeManager:    @PostConstruct
    public void startPollingNodeStates()
    {
        nodeStateUpdateExecutor.scheduleWithFixedDelay(() -> {
            try {
                pollWorkers();
            }
            catch (Exception e) {
                log.error(e, "Error polling state of nodes");
            }
        }, 5, 5, TimeUnit.SECONDS);
        pollWorkers();
    }