[jira] [Created] (YARN-4120) FSAppAttempt.getResourceUsage() should not take preemptedResource into account

["Xianyin Xin (JIRA)" <ji...@apache.org>]

Xianyin Xin created YARN-4120:
---------------------------------

             Summary: FSAppAttempt.getResourceUsage() should not take preemptedResource into account
                 Key: YARN-4120
                 URL: https://issues.apache.org/jira/browse/YARN-4120
             Project: Hadoop YARN
          Issue Type: Bug
          Components: fairscheduler
            Reporter: Xianyin Xin


When compute resource usage for Schedulables, the following code is envolved,
{{FSAppAttempt.getResourceUsage}},
{code}
public Resource getResourceUsage() {
  return Resources.subtract(getCurrentConsumption(), getPreemptedResources());
}
{code}
and this value is aggregated to FSLeafQueues and FSParentQueues. In my opinion, taking {{preemptedResource}} into account here is not reasonable, there are two main reasons,
# it is something in future, i.e., even though these resources are marked as preempted, it is currently used by app, and these resources will be subtracted from {{currentCosumption}} once the preemption is finished. it's not reasonable to make arrange for it ahead of time. 
# there's another problem here, consider following case,
{code}
            root
           /    \
      queue1   queue2
      /    \
queue1.3, queue1.4
{code}
suppose queue1.3 need resource and it can preempt resources from queue1.4, the preemption happens in the interior of queue1. But when compute resource usage of queue1, {{queue1.resourceUsage = it's_current_resource_usage - preemption}} according to the current code, which is unfair to queue2 when doing resource allocating.



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