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Posted to mapreduce-issues@hadoop.apache.org by "James Xu (JIRA)" <ji...@apache.org> on 2013/10/08 08:21:55 UTC

[jira] [Commented] (MAPREDUCE-1700) User supplied dependencies may conflict with MapReduce system JARs

    [ https://issues.apache.org/jira/browse/MAPREDUCE-1700?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13788955#comment-13788955 ] 

James Xu commented on MAPREDUCE-1700:
-------------------------------------

Hi Tom, can you elaborate more on why "org.apache.commons.logging.,org.apache.log4j." should be blacklisted? we are trying to do the similar class loader thing for another software, so want to learn some experience here :)

> User supplied dependencies may conflict with MapReduce system JARs
> ------------------------------------------------------------------
>
>                 Key: MAPREDUCE-1700
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-1700
>             Project: Hadoop Map/Reduce
>          Issue Type: Bug
>          Components: task
>            Reporter: Tom White
>            Assignee: Tom White
>             Fix For: 2.0.3-alpha
>
>         Attachments: MAPREDUCE-1700-ccl.patch, MAPREDUCE-1700-ccl.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch, MAPREDUCE-1700.patch
>
>
> If user code has a dependency on a version of a JAR that is different to the one that happens to be used by Hadoop, then it may not work correctly. This happened with user code using a different version of Avro, as reported [here|https://issues.apache.org/jira/browse/AVRO-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12852081#action_12852081].
> The problem is analogous to the one that application servers have with WAR loading. Using a specialized classloader in the Child JVM is probably the way to solve this.



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