presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/ShardEjector.java/ShardEjector/start
class ShardEjector:    @PostConstruct
    public void start()
    {
        if (!backupStore.isPresent()) {
            return;
        }
        if (!started.getAndSet(true)) {
            startJob();
        }
    }