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https://issues.apache.org/jira/browse/OOZIE-2890?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16017678#comment-16017678
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Robert Kanter commented on OOZIE-2890:
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[~rohini], IMO we shouldn't add this. It's very hacky and encourages the user
to load in incompatible/conflicting jars and rely on classpath ordering, which
is bad. I would rather add classpath isolation in the Launcher AM. Looking at
{{mapreduce.job.classloader}} and {{mapreduce.job.classloader.system.classes}},
which I hadn't heard of, it sounds like those kind of do that already by using
a separate classloader. I'd be more in favor of this (OOZIE-2891). That said,
while this makes sense for something like the Java Action, I'm not sure this
makes sense for other actions where we don't typically execute user jars (e.g.
Hive action).
I'd rather see us add better tools for making it easier for users to detect or
debug classpath issues instead. I know that [~pbacsko] has been looking into a
few ideas, including a custom class loader that detects conflicts and
[jhades|http://jhades.github.io/].
> Implement the equivalent of mapreduce.task.classpath.user.precedence
> --------------------------------------------------------------------
>
> Key: OOZIE-2890
> URL: https://issues.apache.org/jira/browse/OOZIE-2890
> Project: Oozie
> Issue Type: Sub-task
> Reporter: Peter Bacsko
>
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