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https://issues.apache.org/jira/browse/YARN-3388?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14544602#comment-14544602
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Wangda Tan commented on YARN-3388:
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Thanks updating [~nroberts], took at look at latest patch, some comments:
1) It may be better to rename rbl to partitionResource in a couple of places, 
rbl is not a very clear name to me.

2) One bigger problem is, updateClusterResource only considered NO_LABEL, but 
computeUserLimit uses getUsageRatio for all partitions. It will be inaccurate 
if resource of partition updated.
Solution could be:
a. Only use getUsageRatio when partition=NO_LABEL
b. Recomputes all partitions when updateClusterResource.

I prefer b since other code path in your patch are all considered partitions. 
You can take a look at CSQueueUtils#updateQueueStatistics, they should have 
very similar logic to handle partitions when cluster resource updates.

3) It's better not put the user-usage-ratio in ResourceUsage, ResourceUsage is 
targeting to track common resources for user/app/queue. I suggest to create a 
ResourceUsage-like structure in LeafQueue, and User/LeafQueue will share it. 

4) Better to split and rename User.updateUsageRatio to 
User.updateAndGetDeltaOfDominateResourceRatio and 
User.updateAndGetDominateResourceRatio, the "reset" parameter is not very 
straight-forward to me. 



> Allocation in LeafQueue could get stuck because DRF calculator isn't well 
> supported when computing user-limit
> -------------------------------------------------------------------------------------------------------------
>
>                 Key: YARN-3388
>                 URL: https://issues.apache.org/jira/browse/YARN-3388
>             Project: Hadoop YARN
>          Issue Type: Bug
>          Components: capacityscheduler
>    Affects Versions: 2.6.0
>            Reporter: Nathan Roberts
>            Assignee: Nathan Roberts
>         Attachments: YARN-3388-v0.patch, YARN-3388-v1.patch, 
> YARN-3388-v2.patch
>
>
> When there are multiple active users in a queue, it should be possible for 
> those users to make use of capacity up-to max_capacity (or close). The 
> resources should be fairly distributed among the active users in the queue. 
> This works pretty well when there is a single resource being scheduled.   
> However, when there are multiple resources the situation gets more complex 
> and the current algorithm tends to get stuck at Capacity. 
> Example illustrated in subsequent comment.



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