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Posted to issues@hbase.apache.org by "Lars Hofhansl (JIRA)" <ji...@apache.org> on 2012/12/17 07:42:12 UTC

[jira] [Reopened] (HBASE-7336) HFileBlock.readAtOffset does not work well with multiple threads

     [ https://issues.apache.org/jira/browse/HBASE-7336?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Lars Hofhansl reopened HBASE-7336:
----------------------------------


I'll revert this in 0.94 to see whether the OOMs will go away.
(No such problem in 0.96 interestingly)
                
> HFileBlock.readAtOffset does not work well with multiple threads
> ----------------------------------------------------------------
>
>                 Key: HBASE-7336
>                 URL: https://issues.apache.org/jira/browse/HBASE-7336
>             Project: HBase
>          Issue Type: Sub-task
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>            Priority: Critical
>             Fix For: 0.96.0, 0.94.4
>
>         Attachments: 7336-0.94.txt, 7336-0.96.txt
>
>
> HBase grinds to a halt when many threads scan along the same set of blocks and neither read short circuit is nor block caching is enabled for the dfs client ... disabling the block cache makes sense on very large scans.
> It turns out that synchronizing in istream in HFileBlock.readAtOffset is the culprit.

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