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From "Daniel Dai (JIRA)" <j...@apache.org>
Subject [jira] Commented: (PIG-1492) DefaultTuple and DefaultMemory understimate their memory footprint
Date Thu, 15 Jul 2010 20:21:51 GMT

    [ https://issues.apache.org/jira/browse/PIG-1492?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12888905#action_12888905
] 

Daniel Dai commented on PIG-1492:
---------------------------------

Talked with Tejas, he get more observations than listed above. So I believe the formula should
be good. +1 for commit once hudson pass.

> DefaultTuple and DefaultMemory understimate their memory footprint
> ------------------------------------------------------------------
>
>                 Key: PIG-1492
>                 URL: https://issues.apache.org/jira/browse/PIG-1492
>             Project: Pig
>          Issue Type: Bug
>    Affects Versions: 0.8.0
>            Reporter: Thejas M Nair
>            Assignee: Thejas M Nair
>             Fix For: 0.8.0
>
>         Attachments: PIG-1492.1.patch
>
>
> There are several places where we highly underestimate the memory footprint . For example,
for map datatypes, we don't account for the per entry cost for the map container data structures.
The estimated size of a tuple having map with 100 integer key-value entries , as per current
version of code is 3260 bytes, while what is observed is around 6775 bytes .  To verify the
memory footprint, i checked free memory before and after creating multiple instances of the
object , using code on the lines of http://www.javaspecialists.eu/archive/Issue029.html .

> In PIG-1443 similar change was done to fix this for CHARARRAY .

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