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https://issues.apache.org/jira/browse/CRUNCH-604?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15248305#comment-15248305
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Steven Ruppert commented on CRUNCH-604:
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Oops, sorry. I'm not attached to the code in either this or CRUNCH-604--they're
just the first change sets I came across with the desired effect. If you can
think of more holistic fixes, I can help implement them.
> Avoid expensive Writables.reloadWritableComparableCodes where possible
> ----------------------------------------------------------------------
>
> Key: CRUNCH-604
> URL: https://issues.apache.org/jira/browse/CRUNCH-604
> Project: Crunch
> Issue Type: Improvement
> Components: Core
> Affects Versions: 0.13.0
> Reporter: Steven Ruppert
> Assignee: Josh Wills
> Attachments:
> 0001-TupleWritable-only-reload-codes-once-on-setConf.patch,
> 0001-Writables-cache-reloadWritableComparables-when-it-ha.patch
>
>
> Every time `setConf` is called on TupleWritable,
> `Writables.reloadWritableComparableCodes(conf)` is called. Unfortunately,
> `SequenceFile$Reader.readValue` calls `setConf` every single time. This burns
> a regrettable amount of CPU time.
> Attached is a patch that prevents a given TupleWritable instance from
> reloading the code more than once, as well as a patch to cache
> (hashCode-wise) reading from the actual hadoop config, which has to run
> regexes and stuff. I can construe situations where this would break (somehow,
> you modify the configuration in between reading to two values), but nothing
> actually sane comes to mind.
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