dataService.delete(sessionId);
        } catch (final Exception e) {
            logger.warn("Failed to delete data: {}", sessionId, e);
        }
    }

    @Override
    public void run() {
        if (dataService == null) {
            throw new FessSystemException("DataService is null.");
        }

        if (logger.isDebugEnabled()) {
            logger.debug("Starting indexUpdater.");