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https://issues.apache.org/jira/browse/HBASE-18946?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16216366#comment-16216366
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ramkrishna.s.vasudevan commented on HBASE-18946:
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bq.When the Balancer is passed a List, could it look at the list first to find
replicas and group?
It does. But I don't know if it is able to do it across two RPC for the same
table. Will check the balancer logic and see how it can be improved/fixed.
bq.The AssignProcedure is about assigning a single Procedure, nothing else. If
we start bulking it up with other concerns, we'll be back to the fuzzy AMv1
story.
Yes. I am also skeptical about this change and that is the reason why did not
go forward with this patch. I also doubt other issues.
bq.See in RPC where it is batching requests.
Will check. But what I see in AM waitOnAssignQueue() we collect the batched
regions and go with the assignment. Balancer does know about region replicas
but I fear it is still assuming the earlier bulk assign logic. Will be back.
> Stochastic load balancer assigns replica regions to the same RS
> ---------------------------------------------------------------
>
> Key: HBASE-18946
> URL: https://issues.apache.org/jira/browse/HBASE-18946
> Project: HBase
> Issue Type: Bug
> Affects Versions: 2.0.0-alpha-3
> Reporter: ramkrishna.s.vasudevan
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0-beta-1
>
> Attachments: HBASE-18946.patch, HBASE-18946.patch,
> TestRegionReplicasWithRestartScenarios.java
>
>
> Trying out region replica and its assignment I can see that some times the
> default LB Stocahstic load balancer assigns replica regions to the same RS.
> This happens when we have 3 RS checked in and we have a table with 3
> replicas. When a RS goes down then the replicas being assigned to same RS is
> acceptable but the case when we have enough RS to assign this behaviour is
> undesirable and does not solve the purpose of replicas.
> [~huaxiang] and [~enis].
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