neededResources metric in ApplicationResourceUsageReport

[Lei Guo]

>From the name of this metric, I would guess it's for the resource requested by 
>the application. Assuming one application request 10 containers, each with 1G 
>memory and 1 vcore, it should be the total memory/cpu (10G memory, 10 vcores). 
>But from the code, seems it's set with               
>Resources.add(currentConsumption, currentReservation) in 
>scheduler/SchedulerApplicationAttempt.java. Anyone can help to confirm what's 
>the purpose of needResources implemented for?

  public synchronized ApplicationResourceUsageReport getResourceUsageReport() {
    AggregateAppResourceUsage resUsage = getRunningAggregateAppResourceUsage();
    return ApplicationResourceUsageReport.newInstance(liveContainers.size(),
               reservedContainers.size(), Resources.clone(currentConsumption),
               Resources.clone(currentReservation),
               Resources.add(currentConsumption, currentReservation),
               resUsage.getMemorySeconds(), resUsage.getVcoreSeconds());
  }


Have a nice day,
Lei