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https://issues.apache.org/jira/browse/MAPREDUCE-6205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14267371#comment-14267371
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sam liu commented on MAPREDUCE-6205:
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Gera,
The root cause of above failure is that after deserializing both the deprecated
and the non-deprecated versions of a config are set. So, before deserializing,
mapreduce.reduce.java.opts is equals to $ {mapred.child.java.opts}; after
deserializing, mapreduce.reduce.java.opts is equals to '-Xmx200m'.
To resolve this issue, I have a proposal that in mapred-default.xml:
- Comment out the property 'mapred.child.java.opts'
- Uncomment both mapreduce.map|reduce.java.opts and set their value as
'-Xmx200m'.
I think this makes sense, because 'mapred.child.java.opts' is deprecated, but
'mapreduce.map|reduce.java.opts' are recommended by hadoop. With such
modifications, test TestWritableJobConf could pass. Also I ran some other
regarding tests, and I found only test TestJobConf should be updated till now.
What's your comments on the proposal?
Thanks!
> Update the value of the new version properties of the deprecated property
> "mapred.child.java.opts"
> --------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-6205
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-6205
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: mrv2
> Affects Versions: trunk
> Reporter: sam liu
> Assignee: sam liu
> Priority: Minor
> Attachments: MAPREDUCE-6205.patch, MAPREDUCE-6205.patch
>
>
> In current hadoop code, the old property "mapred.child.java.opts" is
> deprecated and its new versions are MRJobConfig.MAP_JAVA_OPTS and
> MRJobConfig.REDUCE_JAVA_OPTS. However, when user set a value to the
> deprecated property "mapred.child.java.opts", hadoop won't automatically
> update its new versions properties
> MRJobConfig.MAP_JAVA_OPTS("mapreduce.map.java.opts") and
> MRJobConfig.REDUCE_JAVA_OPTS("mapreduce.reduce.java.opts"). As hadoop will
> update the new version properties for many other deprecated properties, we
> also should support such feature on the old property
> "mapred.child.java.opts", otherwise it might bring some imcompatible issues.
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