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https://issues.apache.org/jira/browse/MAPREDUCE-2637?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13063940#comment-13063940
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Arun C Murthy commented on MAPREDUCE-2637:
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Devaraj and Harsh - right now, you can specify that subset of maps/reduces be
run with special options to debug/profile only a subset.
I'm pointing out that allowing special denominations for ports etc. is not
necessary since the profiler output can be dumped on local-disk and fetched.
> Providing options to debug the mapreduce user code (Mapper, Reducer,
> Combiner, Sort implementations)
> ----------------------------------------------------------------------------------------------------
>
> Key: MAPREDUCE-2637
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-2637
> Project: Hadoop Map/Reduce
> Issue Type: Improvement
> Components: tasktracker
> Reporter: Devaraj K
> Assignee: Devaraj K
>
> Presently Hadoop provides "mapred.child.java.opts" configuration which can be
> used to set JVM options for Child JVM running Map or Reduce Task.
> If we need to remote debug the Child JVM, we can add remote debugging options
> to this configuration value.
> But this will work only for single Child JVM. Other children will fail as the
> remote debugging port is already used.
> We cannot specify the remote debugging port dynamically.
> As a result, it's not possible to remote debug multiple Child JVMs.
> As a solution to this problem, we can provide a configuration to debug Task
> JVMs in this scenario.
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