code: private void debug(String message, Throwable t) {
  		if (debugEnabled) {
  			long currentTime = System.currentTimeMillis();
  			long timeSinceProcessingStart = currentTime - processingStartedAt;
  			System.err.println(timeSinceProcessingStart + " ["
  				+ localClusterName + "] " + message);
  
  			if (t != null) {
  				t.printStackTrace(System.err);
  			}
  		}
  	}
docs: Prints debug information if the debug is enabled
  
  @param message
  - the debug message
  @param t
  - the instance of Throwable