executor = newFixedThreadPool(nThreads < 1 ? 1 : nThreads);
        final FessConfig fessConfig = ComponentUtil.getFessConfig();
        maxDeleteDocumentCacheSize = fessConfig.getIndexerDataMaxDeleteCacheSizeAsInteger();
        maxRedirectCount = fessConfig.getIndexerDataMaxRedirectCountAsInteger();
    }

    /**
     * Creates a new fixed thread pool executor with the specified number of threads.
     *

     * @return The value of found property. (NotNull: if not found, exception but basically no way)
     * @throws NumberFormatException When the property is not integer.
     */
    Integer getIndexerDataMaxDeleteCacheSizeAsInteger();

    /**
     * Get the value for the key 'indexer.data.max.redirect.count'. <br>
     * The value is, e.g. 10 <br>
     * comment: Maximum redirect count for data in the indexer.