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https://issues.apache.org/jira/browse/HBASE-20933?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vishal Khandelwal updated HBASE-20933:
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    Attachment: Test123.java

> multiple splits may result into forever uncleaned split region
> --------------------------------------------------------------
>
>                 Key: HBASE-20933
>                 URL: https://issues.apache.org/jira/browse/HBASE-20933
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Vishal Khandelwal
>            Assignee: Vishal Khandelwal
>            Priority: Major
>         Attachments: Test123.java
>
>
> Incase of multiple subsequent split and with an open handle on old reference 
> file, it may result into split region which can never be cleaned
>  So Here are two issues.
>  # Region is getting split even when it has reference to its parent
>  # Region is going offline/in archive mode even when there are reference 
> pending in store
> *Repro Steps*
>  # Region split (P)
>  # Before major compaction starts after split, open a handle on store file on 
> new region (DA & DB)
>  # Let compaction completes on DA, (Here compaction will not clear reference 
> store files as it is opened)
>  # Split new region (DA) again ( shouldSplit will return true as before 
> compaction even does the cleanup, it removes the compacted files and 
> reference in-memory list)
>  # Now CatalogJanitor will not remove this region as it has store references, 
> majorCompaction/CompactedHFilesDischarger will not do the cleanup as it only 
> looks at only online regions
>  #  After above steps region-DA which is offline will always be in split 
> regions and never getting cleaned up.
> We found that catalog janitor is also not able to clean regions which are 
> offline(split parent) because it has reference of the daughter of it's parent 
> which is not getting cleaned up. This is causing lot of store files not 
> getting cleaned causing more space in local index store and lot of split 
> lingering regions.
> Unit test repro the scenario has been attached.
> Fix can be in CompactedHFilesDischarger to look into offline region or stop 
> split in such cases.



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