presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/storage/organization/ShardOrganizer.java/ShardOrganizer/ShardOrganizer
class ShardOrganizer:    public ShardOrganizer(JobFactory jobFactory, int threads)
    {
        checkArgument(threads > 0, "threads must be > 0");
        this.jobFactory = requireNonNull(jobFactory, "jobFactory is null");
        this.executorService = newFixedThreadPool(threads, daemonThreadsNamed("shard-organizer-%s"));
        this.executorMBean = new ThreadPoolExecutorMBean((ThreadPoolExecutor) executorService);
    }