presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/BucketBalancer.java/BucketBalancer/start
class BucketBalancer:    @PostConstruct
    public void start()
    {
        if (enabled && backupAvailable && coordinator && !started.getAndSet(true)) {
            executor.scheduleWithFixedDelay(this::runBalanceJob, interval.toMillis(), interval.toMillis(), MILLISECONDS);
        }
    }