[jira] [Commented] (TEZ-2198) Fix sorter spill counts

["Rajesh Balamohan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/TEZ-2198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14726889#comment-14726889 ] 

Rajesh Balamohan commented on TEZ-2198:
---------------------------------------

Committed to branch-0.7
>>>
commit aa767b90ee11477fd45ac25897c41c21b810019a
>>>

> Fix sorter spill counts
> -----------------------
>
>                 Key: TEZ-2198
>                 URL: https://issues.apache.org/jira/browse/TEZ-2198
>             Project: Apache Tez
>          Issue Type: Improvement
>            Reporter: Rajesh Balamohan
>            Assignee: Rajesh Balamohan
>             Fix For: 0.8.0-alpha, 0.7.1
>
>         Attachments: TEZ-2198.1.patch, TEZ-2198.2.patch, TEZ-2198.3.patch, TEZ-2198.4.patch, TEZ-2198.5.patch, TEZ-2198.6.patch, TEZ-2198.branch-0.7.patch, no_additional_spills_eg_pipelined_shuffle.png, with_additional_spills.png
>
>
> Prior to pipelined shuffle, tez merged all spilled data into a single file.  This ended up creating one index file and one output file. In this context, TaskCounter.ADDITIONAL_SPILL_COUNT was referred as the number of additional spills and there was no counter needed to track the number of merges.
> With pipelined shuffle, there is no final merge and ADDITIONAL_SPILL_COUNT would be misleading, as these spills are direct output files which are consumed by the consumers.
> It would be good to have the following 
> - ADDITIONAL_SPILL_COUNT: represents the spills that are needed by the task to generate the final merged output
> - TOTAL_SPILLS: represents the total number of shuffle directories (index + output files) that got created at the end of processing.
> For e.g, Assume sorter generated 5 spills in an attempt
> Without pipelining:
> ==============
> ADDITIONAL_SPILL_COUNT = 5 <-- Additional spills involved in sorting
> TOTAL_SPILLS = 1 <-- Final merged output
> With pipelining:
> ============
> ADDITIONAL_SPILL_COUNT = 0 <-- Additional spills involved in sorting
> TOTAL_SPILLS = 5 <--- all spills are final output



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