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Date: Sun, 27 Jan 2008 00:47:34 -0800 (PST)
From: "Jim Kellerman (JIRA)" <jira@apache.org>
To: hadoop-dev@lucene.apache.org
Subject: [jira] Commented: (HADOOP-2636) [hbase] Make cache flush triggering
 less simplistic
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    [ https://issues.apache.org/jira/browse/HADOOP-2636?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12562969#action_12562969 ] 

Jim Kellerman commented on HADOOP-2636:
---------------------------------------

Thanks for trying this out Billy, as it turned out, the HStore could queue several requests to flush itself before the flusher could act on it. I have modified this so that if an HStore is in the flush queue, it won't get entered a second time.

The latest patch contains this fix.

Additionally, I have re-written Leases to be event-driven rather than a polling model.

If you get a chance, try it out. 

> [hbase] Make cache flush triggering less simplistic
> ---------------------------------------------------
>
>                 Key: HADOOP-2636
>                 URL: https://issues.apache.org/jira/browse/HADOOP-2636
>             Project: Hadoop Core
>          Issue Type: Improvement
>          Components: contrib/hbase
>    Affects Versions: 0.16.0
>            Reporter: stack
>            Assignee: Jim Kellerman
>             Fix For: 0.17.0
>
>         Attachments: patch.txt, patch.txt
>
>
> When flusher runs -- its triggered when the sum of all Stores in a Region > a configurable max size -- we flush all Stores though a Store memcache might have but a few bytes.
> I would think Stores should only dump their memcache disk if they have some substance.
> The problem becomes more acute, the more families you have in a Region.
> Possible behaviors would be to dump the biggest Store only, or only those Stores > 50% of max memcache size.  Behavior would vary dependent on the prompt that provoked the flush.  Would also log why the flush is running: optional or > max size.
> This issue comes out of HADOOP-2621.

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