code: private void showNumTaskPerHeartBeatOption(
            PrintWriter out, boolean advancedView) {
  
      out.print("<h2>Number of Assigned Tasks Per HeartBeat</h2>\n");
      out.printf("<p>Number of map tasks assigned per heartbeat:%s",
                  generateSelect(Arrays.asList("1,2,3,4,5,6,7,8,9,10".split(",")),
                                 scheduler.getMapPerHeartBeat() + "",
                                 "/fairscheduler?setMapPerHeartBeat=<CHOICE>" +
                                 (advancedView ? "&advanced" : "")));
  
      out.printf("<p>Number of reduce tasks assigned per heartbeat:%s",
                 generateSelect(Arrays.asList("1,2,3,4,5,6,7,8,9,10".split(",")),
                                scheduler.getReducePerHeartBeat() + "",
                                "/fairscheduler?setReducePerHeartBeat=<CHOICE>" +
                                (advancedView ? "&advanced" : "")));
    }
docs: Print the UI that allows us to change the number of tasks assigned per
  heartbeat.