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From "Anoop Sam John (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-18166) [AMv2] We are splitting already-split files
Date Tue, 06 Jun 2017 05:08:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-18166?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16038191#comment-16038191

Anoop Sam John commented on HBASE-18166:

Changes in logging for debug purpose, some might not be needed right?
Just trying to understand more.  So we have isSplittable being used which says NO to split
if there are ref files.    Now the change is when we list files for split, we exclude the
ref type files.   So what if a split happened and ref files are split file refes?  Those also
we will exclude from split and go ahead with split?   We had to exclude the to be archived
files which are already compacted away.  Is this new check more generic than it has to be?

> [AMv2] We are splitting already-split files
> -------------------------------------------
>                 Key: HBASE-18166
>                 URL: https://issues.apache.org/jira/browse/HBASE-18166
>             Project: HBase
>          Issue Type: Bug
>          Components: Region Assignment
>    Affects Versions: 2.0.0
>            Reporter: stack
>            Assignee: stack
>             Fix For: 2.0.0
>         Attachments: HBASE-18166.master.001.patch
> Interesting issue. The below adds a lag cleaning up files after a compaction in case
of on-going Scanners (for read replicas/offheap).
> HBASE-14970 Backport HBASE-13082 and its sub-jira to branch-1 - recommit (Ram)
> What the lag means is that now that split is run from the HMaster in master branch, when
it goes to get a listing of the files to split, it can pick up files that are for archiving
but that have not been archived yet.  When it does, it goes ahead and splits them... making
references of references.
> Its a mess.
> I added asking the Region if it is splittable a while back. The Master calls this from
SplitTableRegionProcedure during preparation. If the RegionServer asked for the split, it
is sort of redundant work given the RS asks itself if any references still; if any, it'll
wait before asking for a split. But if a user/client asks, then this isSplittable over RPC
comes in handy.
> I was thinking that isSplittable could return list of files.... 
> Or, easier, given we know a region is Splittable by the time we go to split the files,
then I think master-side we can just skip any references found presuming read-for-archive.
> Will be back with a patch. Want to test on cluster first (Side-effect is regions are
offline because file at end of the reference to a reference is removed ... and so the open

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