[jira] [Updated] (MAPREDUCE-4229) Counter names' memory usage can be decreased by interning

["Vinod Kumar Vavilapalli (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4229?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vinod Kumar Vavilapalli updated MAPREDUCE-4229:
-----------------------------------------------

    Summary: Counter names' memory usage can be decreased by interning  (was: Intern counter names in the JT)

Changing description to reflect the problem and the corresponding code changes.
                
> Counter names' memory usage can be decreased by interning
> ---------------------------------------------------------
>
>                 Key: MAPREDUCE-4229
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4229
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: jobtracker
>    Affects Versions: 1.0.2, 3.0.0, 2.0.2-alpha
>            Reporter: Todd Lipcon
>             Fix For: 3.0.0, 2.0.3-alpha, 0.23.5
>
>         Attachments: MAPREDUCE-4229-branch-0.23.patch, MAPREDUCE-4229-branch-0.23.patch, MAPREDUCE-4229.patch, mr-4229.txt, MR-4229.txt
>
>
> In our experience, most of the memory in production JTs goes to storing counter names (String objects and character arrays). Since most counter names are reused again and again, it would be a big memory savings to keep a hash set of already-used counter names within a job, and refer to the same object from all tasks.

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