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From "Jimmy Xiang (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6611) Forcing region state offline cause double assignment
Date Thu, 27 Sep 2012 22:15:07 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6611?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13465153#comment-13465153
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Jimmy Xiang commented on HBASE-6611:
------------------------------------

Cool, thanks.

There is one problem with the patch I am still thinking about.

In the bulk assignment, I keep the async ZK node offline for the performance reason.  However,
it depends on the zk event thread's callback to know if all nodes are created or not.  If
the single event thread is blocked due to any locker which is held by the bulk assigner, there
will be a deadlock.

What should we do about this?

Instead of async ZK node offline, I am thinking to have an executor service to sync ZK node
offline so that we don't have too much performance degrade.


                
> Forcing region state offline cause double assignment
> ----------------------------------------------------
>
>                 Key: HBASE-6611
>                 URL: https://issues.apache.org/jira/browse/HBASE-6611
>             Project: HBase
>          Issue Type: Bug
>          Components: master
>            Reporter: Jimmy Xiang
>            Assignee: Jimmy Xiang
>             Fix For: 0.96.0
>
>
> In assigning a region, assignment manager forces the region state offline if it is not.
This could cause double assignment, for example, if the region is already assigned and in
the Open state, you should not just change it's state to Offline, and assign it again.
> I think this could be the root cause for all double assignments IF the region state is
reliable.
> After this loophole is closed, TestHBaseFsck should come up a different way to create
some assignment inconsistencies, for example, calling region server to open a region directly.


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