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https://issues.apache.org/jira/browse/HBASE-20332?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16440903#comment-16440903
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Sean Busbey commented on HBASE-20332:
-------------------------------------
one additional note on the "especially #1 and #2 above", the current text in
the section on mapreduce classpaths expressly tell folks to do what #1 and #2
say to do wrt how MR jobs should be invoked in the Hadoop framework, they just
leave out the newer "yarn job" in favor of the older "hadoop job" invocation.
If time, I'll try to see when "yarn job" got added and make a note of it.
> shaded mapreduce module shouldn't include hadoop
> ------------------------------------------------
>
> Key: HBASE-20332
> URL: https://issues.apache.org/jira/browse/HBASE-20332
> Project: HBase
> Issue Type: Sub-task
> Components: mapreduce, shading
> Affects Versions: 2.0.0
> Reporter: Sean Busbey
> Assignee: Sean Busbey
> Priority: Critical
> Fix For: 2.0.0
>
> Attachments: HBASE-20332.0.patch
>
>
> AFAICT, we should just entirely skip including hadoop in our shaded mapreduce
> module
> 1) Folks expect to run yarn / mr apps via {{hadoop jar}} / {{yarn jar}}
> 2) those commands include all the needed Hadoop jars in your classpath by
> default (both client side and in the containers)
> 3) If you try to use "user classpath first" for your job as a workaround
> (e.g. for some library your application needs that hadoop provides) then our
> inclusion of *some but not all* hadoop classes then causes everything to fall
> over because of mixing rewritten and non-rewritten hadoop classes
> 4) if you don't use "user classpath first" then all of our
> non-relocated-but-still-shaded hadoop classes are ignored anyways so we're
> just wasting space
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