*/
        protected Queue<OpenSearchUrlQueue> crawlingQueue = new ConcurrentLinkedQueue<>();
    }

    /**
     * Sets the polling fetch size.
     * @param pollingFetchSize The polling fetch size.
     */
    public void setPollingFetchSize(final int pollingFetchSize) {
        this.pollingFetchSize = pollingFetchSize;
    }

    /**

            crawler.getCrawlerContext().setNumOfThread(numOfThread);
            final String sessionId = crawler.execute();

            // Wait for crawler to start running with polling
            long startTime = System.currentTimeMillis();
            while (crawler.crawlerContext.getStatus() != CrawlerStatus.RUNNING && System.currentTimeMillis() - startTime < 5000) {
                try {

            crawler.getCrawlerContext().setNumOfThread(numOfThread);
            final String sessionId = crawler.execute();

            // Wait for crawler to start running with polling
            long startTime = System.currentTimeMillis();
            while (crawler.crawlerContext.getStatus() != CrawlerStatus.RUNNING && System.currentTimeMillis() - startTime < 5000) {
                try {

 *   <li>Deleting URL queues associated with a session.</li>
 *   <li>Deleting all URL queues.</li>
 *   <li>Offering a list of URLs to the queue, ensuring duplicates are not added.</li>
 *   <li>Polling (retrieving and removing) a URL from the queue.</li>
 *   <li>Saving the session (currently a no-op).</li>
 *   <li>Checking if a URL has already been visited.</li>