presto-accumulo/src/main/java/io/prestosql/plugin/accumulo/index/IndexLookup.java/IndexLookup/IndexLookup
class IndexLookup:    @Inject
    public IndexLookup(Connector connector, ColumnCardinalityCache cardinalityCache)
    {
        this.connector = requireNonNull(connector, "connector is null");
        this.cardinalityCache = requireNonNull(cardinalityCache, "cardinalityCache is null");

        // Create a bounded executor with a pool size at 4x number of processors
        this.coreExecutor = newCachedThreadPool(daemonThreadsNamed("cardinality-lookup-%s"));
        this.executorService = new BoundedExecutor(coreExecutor, 4 * Runtime.getRuntime().availableProcessors());
    }