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https://issues.apache.org/jira/browse/HADOOP-7339?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Todd Lipcon updated HADOOP-7339:
--------------------------------
Fix Version/s: (was: 0.22.0)
0.23.0
bumping to 0.23 since this is an optimization
> Introduce a buffered checksum for avoiding frequently calls on
> Checksum.update()
> --------------------------------------------------------------------------------
>
> Key: HADOOP-7339
> URL: https://issues.apache.org/jira/browse/HADOOP-7339
> Project: Hadoop Common
> Issue Type: Improvement
> Components: util
> Reporter: Min Zhou
> Fix For: 0.23.0
>
> Attachments: HADOOP-7339-v1.diff, HADOOP-7339-v2.diff
>
>
> We found that PureJavaCRC32/CRC32.update() is the TOP 1 of the methods
> consuming CPU in a map side, and in reduce side, it cost a lots of CPU too.
> IFileOutputStream would frequently call Checksum.update() during writing a
> record. It's very common a MR key/value less than 512 bytes.
> Checksum.update() would be called every time writing a key/value.
> Test case: terasort 100MB.
> Checksum.update() calls has be reduced from 4030348 to 28069. This method is
> not a hotspot anymore.
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