[jira] [Commented] (TEZ-2574) Make a better Metadata Value split choice in Pipeline sort

["Hitesh Shah (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-2574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15440017#comment-15440017 ] 

Hitesh Shah commented on TEZ-2574:
----------------------------------

[~rajesh.balamohan] Any comments on how to get this to completion? 

> Make a better Metadata Value split choice in Pipeline sort
> ----------------------------------------------------------
>
>                 Key: TEZ-2574
>                 URL: https://issues.apache.org/jira/browse/TEZ-2574
>             Project: Apache Tez
>          Issue Type: Improvement
>            Reporter: Saikat
>            Assignee: Saikat
>         Attachments: TEZ-2574.1.patch, TEZ-2574.2.patch, TEZ-2574.3.patch, TEZ-2574.patch
>
>
> In the current implementation of pipeline sort, when a new sort span object is created with a hard coded value of 1M items and 16 bytes per item.
> According to the present code logic, 
>       int metasize = METASIZE*maxItems;
>       int dataSize = maxItems * perItem;
>       if(capacity < (metasize+dataSize)) {
>         // try to allocate less meta space, because we have sample data
>         metasize = METASIZE*(capacity/(perItem+METASIZE));
>       }
> if capacity is less than 32mb, the buffer will be halved into meta and value buffers, which is not efficient.
> We need a more generic split, based on the KV pair size written to the buffer.



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