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Date: Thu, 13 Dec 2012 19:34:12 +0000 (UTC)
From: "Andrew Purtell (JIRA)" <jira@apache.org>
To: issues@hbase.apache.org
Message-ID: <JIRA.12623618.1355344492217.2412.1355427252762@arcas>
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Subject: [jira] [Commented] (HBASE-7340) Master coprocessor notification for
 assignmentManager.balance() is inconsistent
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    [ https://issues.apache.org/jira/browse/HBASE-7340?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13531367#comment-13531367 ] 

Andrew Purtell commented on HBASE-7340:
---------------------------------------

[~saint.ack@gmail.com] I think this is some minor missing coverage in the CP API, minor because there isn't an existing user (yet) for it, so it's reasonable on those grounds. Agree the priority should be minor if not trivial.
                
> Master coprocessor notification for assignmentManager.balance() is inconsistent
> -------------------------------------------------------------------------------
>
>                 Key: HBASE-7340
>                 URL: https://issues.apache.org/jira/browse/HBASE-7340
>             Project: HBase
>          Issue Type: Bug
>            Reporter: Ted Yu
>            Assignee: Ted Yu
>         Attachments: 7340-v1.txt
>
>
> I found this issue when reading user discussion which is quoted below.
> In HMaster.moveRegion(), we have:
> {code}
>       this.assignmentManager.balance(rp);
>       if (this.cpHost != null) {
>         this.cpHost.postMove(hri, rp.getSource(), rp.getDestination());
>       }
> {code}
> Meaning, user can register master coprocessor which would receive region movement notification.
> The assignmentManager.balance(plan) call in HMaster.balance() doesn't send out such notification.
> I think we should enhance the following hook (at line 1335) with list of regions moved so that notification from master is consistent:
> {code}
>         this.cpHost.postBalance();
> {code}
> Here is excerpt for user discussion:
> Sometimes user performs compaction after a region is moved (by balancer). We should provide 'hook' which lets user specify what follow-on actions to take after region movement.
> See discussion on user mailing list under the thread 'How to know it's time for a major compaction?' for background information: http://search-hadoop.com/m/BDx4S1jMjF92&subj=How+to+know+it+s+time+for+a+major+compaction+

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