code: private void dumpStatus(long now) {
      if (now - lastDumpStatusTime < dumpStatusPeriod) {
        return;
      }
      lastDumpStatusTime = now;
      logJobStats(infos.keySet(), TaskType.MAP);
      logJobStats(infos.keySet(), TaskType.REDUCE);
      dumpSpeculationStatus(now);
    }
docs: Output some scheduling information to LOG
  @param now current unix time