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https://issues.apache.org/jira/browse/MAPREDUCE-4365?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13401803#comment-13401803
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Jie Li commented on MAPREDUCE-4365:
-----------------------------------
Thanks Arun and Robert.
I meant profiling tasks and actually I'm using [Hadoop
profiling|http://hadoop.apache.org/common/docs/r0.20.2/mapred_tutorial.html#Profiling]
by setting mapred.task.profile.{maps|reduces} so Hadoop will automatically
send back the profiling output files.
The reason why your approach couldn't work is that, currently it is task's
responsibility to set up the symlink for the distributed cache, so when TT
launches the task, the symlink is not set up yet. Note TaskRunner#setupWorkDir
is called in Child#main.
So one solution is to create the symlink before launching tasks, or we can
replace the distributed cache entry found in the profiling parameters with the
localized path for this particular problem?
> Shipping Profiler Libraries by DistributedCache
> -----------------------------------------------
>
> Key: MAPREDUCE-4365
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4365
> Project: Hadoop Map/Reduce
> Issue Type: New Feature
> Affects Versions: 1.0.3
> Reporter: Jie Li
>
> Hadoop profiling is great for performance tuning and debugging, but currently
> we can only use Java built-in profilers such as HProf, and for other
> profilers we need to install them on all slave nodes first, which is
> inconvenient for large clusters and sometimes impossible for production
> clusters.
> Supporting shipping profiler libraries using DistributedCache will solve this
> problem. For example, in mapred.task.profile.params, we specify a profiler
> library from the DistributedCache using special place holders such as
> <foo.jar>, and Hadoop can look at the DistributedCache to replace <foo.jar>
> with the localized path before launching the child jvm.
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