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From "Todd Lipcon (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (MAPREDUCE-4229) Intern counter names in the JT
Date Mon, 07 May 2012 03:12:13 GMT

    [ https://issues.apache.org/jira/browse/MAPREDUCE-4229?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13269341#comment-13269341
] 

Todd Lipcon commented on MAPREDUCE-4229:
----------------------------------------

Hi Steve. I am suggesting using a GettableSet<String> per JobInProgress, rather than
actually calling String.intern. That way the stuff might make it to old-gen, but won't ever
go to perm.
                
> Intern counter names in the JT
> ------------------------------
>
>                 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
>            Reporter: Todd Lipcon
>
> 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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