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From "nkeywal (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-7247) Assignment performances decreased by 50% because of regionserver.OpenRegionHandler#tickleOpening
Date Wed, 05 Dec 2012 10:05:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-7247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13510389#comment-13510389
] 

nkeywal commented on HBASE-7247:
--------------------------------

The issue comes from mixing asynchronous writes with synchronous writes & reads. My patch
is now working but adds some complexity because of the added resynchronisation. I'm gonna
do simpler. The ideal solution would be to be full async for the region opening (and I'm not
gonna do that here :-) )
                
> Assignment performances decreased by 50% because of regionserver.OpenRegionHandler#tickleOpening
> ------------------------------------------------------------------------------------------------
>
>                 Key: HBASE-7247
>                 URL: https://issues.apache.org/jira/browse/HBASE-7247
>             Project: HBase
>          Issue Type: Improvement
>          Components: master, Region Assignment, regionserver
>    Affects Versions: 0.96.0
>            Reporter: nkeywal
>            Assignee: nkeywal
>            Priority: Critical
>
> The regionserver.OpenRegionHandler#tickleOpening updates the region znode as "Do this
so master doesn't timeout this region-in-transition.".
> However, on the usual test, this makes the assignment time of 1500 regions goes from
70s to 100s, that is, we're 50% slower because of this.
> More generally, ZooKeper commits to disk all the data update, and this takes time. Using
it to provide a keep alive seems overkill. At the very list, it could be made asynchronous.
> I'm not sure how necessary these updates are required (I need to go deeper in the internal,
feedback welcome), but it seems very important to optimize this... The trival fix would be
to make this optional.

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