code: public static void startPollingForMessages(final String queueURL) {
  		if (!StringUtils.isBlank(queueURL) && !POLLING_THREADS.containsKey(queueURL)) {
  			logger.info("Starting SQS river using queue {} (polling interval: {}s)", queueURL, POLLING_INTERVAL);
  			POLLING_THREADS.putIfAbsent(queueURL, Para.getExecutorService().submit(new SQSRiver(queueURL)));
  			Para.addDestroyListener(new DestroyListener() {
  				public void onDestroy() {
  					stopPollingForMessages(queueURL);
  				}
  			});
  		}
  	}
docs: Starts polling for messages from SQS in a separate thread.
  @param queueURL a queue URL