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From "Jean-Daniel Cryans (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-8420) Port HBASE-6874 Implement prefetching for scanners from 0.89-fb
Date Mon, 13 May 2013 20:59:17 GMT

    [ https://issues.apache.org/jira/browse/HBASE-8420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13656370#comment-13656370
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Jean-Daniel Cryans commented on HBASE-8420:
-------------------------------------------

On the latest patch:

 - I think you have a leak if the client doesn't come back to get the prefetched data, at
least you should decrement globalPrefetchedResultSize in RegionScannerHolder.closeScanner().
 - 512MB seems big, I'd be more comfortable with 128MB.
 - Is it possible to unit test this?
 - Have you run a concurrent workload against capped pre-fetching?
 - Should we report on the state of globalPrefetchedResultSize? I'm wondering what could be
helpful to see when debugging scan slowness WRT this rate limiting. Maybe a TRACE every time
we skip a prefetch and output totalPrefetchedResultSize?
                
> Port  HBASE-6874  Implement prefetching for scanners from 0.89-fb
> -----------------------------------------------------------------
>
>                 Key: HBASE-8420
>                 URL: https://issues.apache.org/jira/browse/HBASE-8420
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: Jimmy Xiang
>            Assignee: Jimmy Xiang
>         Attachments: 0.94-8420_v1.patch, 0.94-8420_v2.patch, trunk-8420_v1.patch, trunk-8420_v2.patch,
trunk-8420_v3.patch
>
>
> This should help scanner performance.  We should have it in trunk.

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