public 
	void stopJobsForPage(AbstractPage page) {
		for (JobFuturePair pair: submittedPairs) 
			// no new tasks will be submitted because of synchronization.
			if (pair.job.page.equals(page)) 
				// we don't remove pair from queue here to not mess up with main JobMaster thread. 
				pair.future.cancel(true);
	}