[jira] [Updated] (MAPREDUCE-4752) Reduce MR AM memory usage through String Interning

["Robert Joseph Evans (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MAPREDUCE-4752?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Robert Joseph Evans updated MAPREDUCE-4752:
-------------------------------------------

    Attachment: MR-4752-branch-0.23.txt
    
> Reduce MR AM memory usage through String Interning
> --------------------------------------------------
>
>                 Key: MAPREDUCE-4752
>                 URL: https://issues.apache.org/jira/browse/MAPREDUCE-4752
>             Project: Hadoop Map/Reduce
>          Issue Type: Improvement
>          Components: mrv2
>            Reporter: Robert Joseph Evans
>            Assignee: Robert Joseph Evans
>         Attachments: MR-4752-branch-0.23.txt
>
>
> There are a lot of strings that are duplicates of one another in the AM.  This comes from all of the PB events the come across the wire and also tasks heart-beating in through the umbilical.  There are even several duplicates from Configuration.  By "interning" all of these strings on the Heap I have been able to reduce the resting memory usage of the AM to be about 5KB per task attempt.  With about half of this coming from counters.  This results in a 5MB heap for a typical 1000 task job, or a 500MB heap for a 100,000 task attempt job.  I think I could cut the size of the counters in half by completely rewriting how counters work in the AM and History Server, but I don't think it is worth it at this point.
> I am still investigating what the memory usage of the AM is like when running very large jobs, and I will probably have a follow-up JIRA for reducing that memory usage as well.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira