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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8502) Eternally stuck Region after split
Date Fri, 10 May 2013 16:59:17 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8502?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13654602#comment-13654602

Jimmy Xiang commented on HBASE-8502:

bq. The daughter region was able to stay offline without any problems
I think it is most likely because the parent is still online so that we don't need the daughter.
The parent may have gone through some compaction so the file is gone. When the parent is split
again, the same daughter region happens to be created, which is not cleaned up properly during
the previous split try which has a ref file leftover which refers to the file is already gone.
 That's my guess.  I will take a look the code to make sure rolling back clean up the daughter

As to move forward, other than reviewing the rolling back code check, I think we can set up
some continuous testing to do region split all the time.  We are sure to be able to reproduce
it, if it is a code issue.
> Eternally stuck Region after split
> ----------------------------------
>                 Key: HBASE-8502
>                 URL: https://issues.apache.org/jira/browse/HBASE-8502
>             Project: HBase
>          Issue Type: Bug
>    Affects Versions: 0.92.1
>            Reporter: Dimitri Goldin
>            Priority: Critical
>         Attachments: hbase_lost_parent.txt, stuck_region_exception.txt
> Exact HBase version: 0.92.1-cdh4.1.2
> A couple of days ago I encountered a RIT problem with a single region.
> After an hbck run it started trying to assign a region which has been 
> bouncing between OFFLINE/PENDING_OPEN/OPENING for two days afterwards.
> This was due to a split gone wrong in some way, which led to several 
> reference files being left in the region-directory despite the two relevant HFiles being
copies successfully to the daughter.
> I will try to give as many details as possible, but unfortunately I was
> unable to find any information about the split itself.
> Short thread about this issue on the users-ML: http://mail-archives.apache.org/mod_mbox/hbase-user/201305.mbox/%3C5182758B.1060306@neofonie.de%3E
> ===
> Parent region: 5b9c16898a371de58f31f0bdf86b1f8b
> Daughter region in question: 79c619508659018ff3ef0887611eb8f7
> Rough sequence from the logs seems to be the following:
> ===
> * Received request to open region:
> documents,7128586022887322720,1363696791400.79c619508659018ff3ef0887611eb8f7.
> * Setting up tabledescriptor config now ...
> * Opening of region {NAME =>
> 'documents,7128586022887322720,1363696791400.79c619508659018ff3ef0887611eb8f7.',
>      STARTKEY => '7128586022887322720',
>      ENDKEY => '7130716361635801616',
>      ENCODED => 79c619508659018ff3ef0887611eb8f7,} failed, marking as 
> * File does not exist: 
> /hbase/documents/5b9c16898a371de58f31f0bdf86b1f8b/d/0707b1ec4c6b41cf9174e0d2a1785fe9

> [...]
> ===
> What happened, was that somehow (and that's the question here) the daughters
> region folder contained some left-over reference files were causing the 
> RegionServer to look-up the parent region, which already was deleted.
> original contents of /hbase/documents/79c619508659018ff3ef0887611eb8f7/d:
> ==
> 0707b1ec4c6b41cf9174e0d2a1785fe9.5b9c16898a371de58f31f0bdf86b1f8b
> 47511faae81b4452afd3ca206e28346f.5b9c16898a371de58f31f0bdf86b1f8b
> 4f01ecd052ce464d81e79a62ea227d6b
> 4f01ecd052ce464d81e79a62ea227d6b.5b9c16898a371de58f31f0bdf86b1f8b
> eb7dbb09701d4353be24ca82481c4a7e
> == 
> I attached the full FileNotFound Exception.
> Please let me know if I can provide more information or help otherwise.

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