[jira] [Closed] (MAPREDUCE-4301) Dedupe some strings in MRAM for memory savings

["Arun C Murthy (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4301?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Arun C Murthy closed MAPREDUCE-4301.
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> Dedupe some strings in MRAM for memory savings
> ----------------------------------------------
>
>                 Key: MAPREDUCE-4301
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4301
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: applicationmaster
>    Affects Versions: 0.23.3, 2.0.0-alpha
>            Reporter: Robert Joseph Evans
>            Assignee: Robert Joseph Evans
>             Fix For: 0.23.3, 2.0.2-alpha
>
>         Attachments: MR-4301.txt
>
>
> Recently an OutOfMemoryError caused one of our jobs to become a zombie (MAPREDUCE-4300).  It was a rather large job with 78000+ map tasks and only 750MB of heap configured.  I took a heap dump to see if there were any obvious memory leaks, and I could not find any, but yourkit and some digging found some potential memory optimizations that we could do.
> In this particular case we could save about 20MB if SplitMetaInfoReader.readSplitMetaInfo only computed the JobSplitFile once instead of for each split. (a 2 line change)
> I will look into some others and see if there are more savings I can come up with.

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