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https://issues.apache.org/jira/browse/HBASE-3872?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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stack updated HBASE-3872:
-------------------------
Attachment: 3872.txt
Not finished but I think best tactic is moving meta edit beyond
point-of-no-return splitting; if it fails at all, crash out the regionserver
and let servershutdownhandler do the fixup. Fixup will now have this second
case to deal with. Do the fixup in one place only. Need to also amend
CatalogJanitor so it does not mistakenly cleanup the parent region.
> Hole in split transaction rollback; edits to .META. need to be rolled back
> even if it seems like they didn't make it
> --------------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-3872
> URL: https://issues.apache.org/jira/browse/HBASE-3872
> Project: HBase
> Issue Type: Bug
> Components: regionserver
> Affects Versions: 0.90.3
> Reporter: stack
> Assignee: stack
> Priority: Critical
> Fix For: 0.90.4
>
> Attachments: 3872.txt
>
>
> Saw this interesting one on a cluster of ours. The cluster was configured
> with too few handlers so lots of the phenomeneon where actions were queued
> but then by the time they got into the server and tried respond to the
> client, the client had disconnected because of the timeout of 60 seconds.
> Well, the meta edits for a split were queued at the regionserver carrying
> .META. and by the time it went to write back, the client had gone (the first
> insert of parent offline with daughter regions added as info:splitA and
> info:splitB). The client presumed the edits failed and 'successfully' rolled
> back the transaction (failing to undo .META. edits thinking they didn't go
> through).
> A few minutes later the .META. scanner on master runs. It sees 'no
> references' in daughters -- the daughters had been cleaned up as part of the
> split transaction rollback -- so it thinks its safe to delete the parent.
> Two things:
> + Tighten up check in master... need to check daughter region at least exists
> and possibly the daughter region has an entry in .META.
> + Dependent on the edit that fails, schedule rollback edits though it will
> seem like they didn't go through.
> This is pretty critical one.
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