@Override
    @PreDestroy
    public void close() throws Exception {
        if (executorService != null) {
            try {
                executorService.shutdown();
                executorService.awaitTermination(60, TimeUnit.SECONDS);
            } catch (final InterruptedException e) {
                if (logger.isDebugEnabled()) {
                    logger.debug("Interrupted.", e);
                }
            } finally {