presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/ShardEjector.java/ShardEjector/startJob
class ShardEjector:    private void startJob()
    {
        executor.scheduleWithFixedDelay(() -> {
            try {
                // jitter to avoid overloading database
                long interval = this.interval.roundTo(SECONDS);
                SECONDS.sleep(ThreadLocalRandom.current().nextLong(1, interval));
                process();
            }
            catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
            catch (Throwable t) {
                log.error(t, "Error ejecting shards");
                jobErrors.update(1);
            }
        }, 0, interval.toMillis(), MILLISECONDS);
    }