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From "Andrew Purtell (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-6841) Meta prefetching is slower than doing multiple meta lookups
Date Thu, 20 Sep 2012 19:51:07 GMT

    [ https://issues.apache.org/jira/browse/HBASE-6841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13459893#comment-13459893
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Andrew Purtell commented on HBASE-6841:
---------------------------------------

Given J-D's observations, perhaps we should default meta prefetch to off, like Stack suggests.


Some time ago I patched our private Frankenbase to allow disable of meta prefetch on a per
table basis. This was because meta prefetch was causing heap limited MR clients to OOME, and
for that particular application table prefetch wasn't helpful.

                
> Meta prefetching is slower than doing multiple meta lookups
> -----------------------------------------------------------
>
>                 Key: HBASE-6841
>                 URL: https://issues.apache.org/jira/browse/HBASE-6841
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Jean-Daniel Cryans
>            Priority: Critical
>             Fix For: 0.94.2
>
>
> I got myself into a situation where I needed to truncate a massive table while it was
getting hits and surprisingly the clients were not recovering. What I see in the logs is that
every time we prefetch .META. we setup a new HConnection because we close it on the way out.
It's awfully slow.
> We should just turn it off or make it useful. jstacks coming up.

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