code: protected synchronized void scheduleReduce(TaskInProgress tip) {
      runningReduceTaskStats.add(0.0f);
      runningTaskCopyProcessingRateStats.add(0.0f);
      runningTaskSortProcessingRateStats.add(0.0f);
      runningTaskReduceProcessingRateStats.add(0.0f);
      if (runningReduces == null) {
        LOG.warn("Running cache for reducers missing!! "
                 + "Job details are missing.");
        return;
      }
      runningReduces.add(tip);
    }
docs: Adds a reduce tip to the list of running reduces
  @param tip the tip that needs to be scheduled as running