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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Created] (MAPREDUCE-4469) Resource calculation in child tasks is CPU-heavy
Date Mon, 23 Jul 2012 20:43:34 GMT
Todd Lipcon created MAPREDUCE-4469:

             Summary: 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

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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