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https://issues.apache.org/jira/browse/YARN-6999?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16131718#comment-16131718
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Li Lu commented on YARN-6999:
-----------------------------
Thanks for the work [~littlestone00], this appears to be a real usability issue
for a lot of new Hadoop developers. Since you have already uploaded a patch,
I'm assigning this JIRA to you. The general direction of the fix looks fine.
Adding log message clearly acknowledge users potential root cause sounds quite
helpful.
One potential issue is that the fix appears to be in node manager's code, but
there is logic specifically for MapReduce. Maybe we can make this error message
less hard-coded? (I'm still thinking about possible ways to improve this but so
far I've got no trivial answer...)
> Add log about how to solve Error: Could not find or load main class
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster
> ------------------------------------------------------------------------------------------------------------------
>
> Key: YARN-6999
> URL: https://issues.apache.org/jira/browse/YARN-6999
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: documentation, security
> Affects Versions: 3.0.0-beta1
> Environment: All operating systems.
> Reporter: Linlin Zhou
> Assignee: Linlin Zhou
> Priority: Minor
> Labels: beginner
> Fix For: 3.0.0-beta1
>
> Attachments: yarn-6999.patch
>
> Original Estimate: 1h
> Remaining Estimate: 1h
>
> According Setting up a Single Node Cluster
> [https://hadoop.apache.org/docs/stable/hadoop-project-dist/hadoop-common/SingleCluster.html],
> we would still failed to run the MapReduce job example. Due to a security
> fix, yarn use user's environment variables to init, and user's environment
> variable usually doesn't include MapReduce related settings. So we need to
> add the related config in etc/hadoop/mapred-site.xml manually. Currently the
> log only tells there is an Error:
> Could not find or load main class
> org.apache.hadoop.mapreduce.v2.app.MRAppMaster, without suggestion on how to
> solve it. I want to add the useful suggestion in log.
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