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https://issues.apache.org/jira/browse/HBASE-6228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13402106#comment-13402106
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chunhui shen commented on HBASE-6228:
-------------------------------------
@ram
Do you run the case in trunk? Maybe case is not good, but I run it and always
failed without patch.
bq.update the region plan we cannot assure that double assignment can be done
If we restart master after fixup daughter, master won't contain any plans, so I
just simulate it and ensure case could happen.
Another thing, I think I must say:
If we send open region RPC twice for one region, but not assigned twice because
we have many protection through version. But we also have risk of data
correctness.
Why?:
When region in opening, it will replay log edits and flush; if two
regionservers do opening region together, could we ensure data correctness?
> Fixup daughters twice cause daughter region assigned twice
> -----------------------------------------------------------
>
> Key: HBASE-6228
> URL: https://issues.apache.org/jira/browse/HBASE-6228
> Project: HBase
> Issue Type: Bug
> Components: master
> Reporter: chunhui shen
> Assignee: chunhui shen
> Fix For: 0.96.0
>
> Attachments: HBASE-6228.patch, HBASE-6228v2.patch,
> HBASE-6228v2.patch, HBASE-6228v3.patch
>
>
> First, how fixup daughters twice happen?
> 1.we will fixupDaughters at the last of HMaster#finishInitialization
> 2.ServerShutdownHandler will fixupDaughters when reassigning region through
> ServerShutdownHandler#processDeadRegion
> When fixupDaughters, we will added daughters to .META., but it coudn't
> prevent the above case, because FindDaughterVisitor.
> The detail is as the following:
> Suppose region A is a splitted parent region, and its daughter region B is
> missing
> 1.First, ServerShutdownHander thread fixup daughter, so add daughter region B
> to .META. with serverName=null, and assign the daughter.
> 2.Then, Master's initialization thread will also find the daughter region B
> is missing and assign it. It is because FindDaughterVisitor consider daughter
> is missing if its serverName=null
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