[jira] [Commented] (HBASE-14738) Backport HBASE-11927 (Use Native Hadoop Library for HFile checksum) to 0.98

["Lars Hofhansl (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HBASE-14738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15374508#comment-15374508 ] 

Lars Hofhansl commented on HBASE-14738:
---------------------------------------

It's interesting that I never see this in my profiling sessions. What's the workload? (I assume uncached reads) 

> Backport HBASE-11927 (Use Native Hadoop Library for HFile checksum) to 0.98
> ---------------------------------------------------------------------------
>
>                 Key: HBASE-14738
>                 URL: https://issues.apache.org/jira/browse/HBASE-14738
>             Project: HBase
>          Issue Type: Task
>            Reporter: Andrew Purtell
>         Attachments: HBASE-14738-0.98.patch
>
>
> Profiling 0.98.15 I see 20-30% of CPU time spent in Hadoop's PureJavaCrc32. Not surprising given previous results described on HBASE-11927. Backport.
> There are two issues with the backport:
> # The patch on 11927 changes the default CRC type from CRC32 to CRC32C. Although the changes are backwards compatible -files with either CRC type will be handled correctly in a transparent manner - we should probably leave the default alone in 0.98 and advise users on a site configuration change to use CRC32C if desired, for potential hardware acceleration.
> # Need a shim for differences between Hadoop's DataChecksum type.



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