indexUpdater.setDaemon(true);
        indexUpdater.setCrawlerList(crawlerList);
        getAvailableBoostDocumentRuleList().forEach(rule -> {
            indexUpdater.addDocBoostMatcher(new org.codelibs.fess.indexer.DocBoostMatcher(rule));
        });
        indexUpdater.start();

        int startedCrawlerNum = 0;
        int activeCrawlerNum = 0;
        try {

    }

    /**
     * Adds a document boost matcher rule for enhancing document relevance scores.
     *
     * @param rule the document boost matcher rule to add
     */
    public void addDocBoostMatcher(final DocBoostMatcher rule) {
        docBoostMatcherList.add(rule);
    }

    /**
     * Sets the list of crawler instances that this updater will manage.
     *