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https://issues.apache.org/jira/browse/TEZ-2198?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14520391#comment-14520391
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Siddharth Seth commented on TEZ-2198:
-------------------------------------
Mostly looks good to me.
Obligatory rename request :) - TOTAL_SPILL_COUNT can be confusing since it
doesn't include the ADDITIONAL_SPILLS, even though the name would indicate this
is a total of all spills. Something like SHUFFLE_CHUNK_COUNT or a name
indicating that these files will be shuffled would be better.
Minor enhancement request - which can be done later would be to increment the
counters as and when spill happens. Allows seeing spill progress on the UI for
a running task.
> 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, TEZ-2198.2.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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