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https://issues.apache.org/jira/browse/TEZ-2198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14363219#comment-14363219
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Gopal V commented on TEZ-2198:
------------------------------
[~rajesh.balamohan]: patch looks good - will test it today & check the counter
values.
One stylistic suggestion is to move the finalMergeEnabled flag to
ExternalSorter as it is an external sorter property effectively, to avoid
having write a VisibleForTesting in that manner.
The merge-sort behaviour is entirely driven from ExternalSorter level,
applicable to both DefaultSorter and PipelinedSorter implementations with the
same meaning.
> 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
> Attachments: TEZ-2198.1.patch
>
>
> 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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