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https://issues.apache.org/jira/browse/MAPREDUCE-4469?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13429604#comment-13429604
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Todd Lipcon commented on MAPREDUCE-4469:
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But a streaming task will only finish once its child process (the actual
streaming workload) has exited. Thus, it won't be part of the process tree
anymore, so it wouldn't be properly accounted.
> Resource calculation in child tasks is CPU-heavy
> ------------------------------------------------
>
> Key: MAPREDUCE-4469
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-4469
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: performance, task
> Affects Versions: 1.0.3
> Reporter: Todd Lipcon
> Assignee: Ahmed Radwan
> Attachments: MAPREDUCE-4469.patch
>
>
> In doing some benchmarking on a hadoop-1 derived codebase, I noticed that
> each of the child tasks was doing a ton of syscalls. Upon stracing, I noticed
> that it's spending a lot of time looping through all the files in /proc to
> calculate resource usage.
> As a test, I added a flag to disable use of the ResourceCalculatorPlugin
> within the tasks. On a CPU-bound 500G-sort workload, this improved total job
> runtime by about 10% (map slot-seconds by 14%, reduce slot seconds by 8%)
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