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

    protected ExecutorService newFixedThreadPool(final int nThreads) {
        if (logger.isDebugEnabled()) {