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https://issues.apache.org/jira/browse/HADOOP-13344?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15371115#comment-15371115
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Thomas Poepping commented on HADOOP-13344:
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The problem is not that the user slf4j binding isn't being used, it's that
slf4j will report an error to stderr : "SLF4J: Class path contains multiple
SLF4J bindings ... etc"
https://github.com/qos-ch/slf4j/blob/c2463021fe0944a03d3fdcc14c3914c86d4a7a4f/slf4j-api/src/main/java/org/slf4j/LoggerFactory.java#L319
This change is to provide users a way around that. We default to *not* using
this option (a bit of iffy not logic, I know), so that we don't unintentionally
hide this error for people it might negatively affect.
To your other points, understood. I'll do some looking into how we can find the
offending slf4j binding in the most platform independent way.
> Add option to exclude Hadoop's SLF4J binding
> --------------------------------------------
>
> Key: HADOOP-13344
> URL: https://issues.apache.org/jira/browse/HADOOP-13344
> Project: Hadoop Common
> Issue Type: New Feature
> Components: bin, scripts
> Affects Versions: 2.8.0, 2.7.2
> Reporter: Thomas Poepping
> Labels: patch
> Attachments: HADOOP-13344.patch
>
>
> If another application that uses the Hadoop classpath brings in its own SLF4J
> binding for logging, and that jar is not the exact same as the one brought in
> by Hadoop, then there will be a conflict between logging jars between the two
> classpaths. This patch introduces an optional setting to remove Hadoop's
> SLF4J binding from the classpath, to get rid of this problem.
> This patch should be applied to 2.8.0, as bin/ and hadoop-config.sh structure
> has been changed in 3.0.0.
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