code: private void reportStatus(String msg, boolean rightNow) {
      long curTime = FSNamesystem.now();
      if (!rightNow && (curTime - lastStatusReport < 20 * 1000)) {
        return;
      }
      FLOG.info(msg + " \n" + getTurnOffTip());
      lastStatusReport = curTime;
    }
docs: Print status every 20 seconds.