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https://issues.apache.org/jira/browse/HIVE-15881?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15864325#comment-15864325
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Thomas Poepping commented on HIVE-15881:
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Spent a little more time looking into this, found the same thing as Sahil. I
would like to suggest some edits:
I would change the naming of the variable. As I said above,
{{hive.get.input.listing.num.threads}} isn't exactly clear, and because this is
used for two things ({{getInputSummary}} and {{getInputPaths}}) I would like to
propose a different way of doing this.
* Two configuration values, one for each usage:
** {{hive.exec.input.paths.num.threads}} for {{getInputPaths}}
** {{hive.exec.input.summary.num.threads}} for {{getInputSummary}}
* Bonus is that these follow existing {{HiveConf}} patterns
Other questions that should be asked:
* what is the default value?
** I'm looking through {{HiveConf}}, but not seeing any other config value that
might suffice. Maybe we just use 1?
Also, I'm a fan of '0' meaning 'maximum number allowable' with these types of
config values, but that can be up for discussion. We would need a way to figure
out what "max allowable" actually _means_, either through another configuration
value or based on the OS structure? I don't know.
> Use new thread count variable name instead of mapred.dfsclient.parallelism.max
> ------------------------------------------------------------------------------
>
> Key: HIVE-15881
> URL: https://issues.apache.org/jira/browse/HIVE-15881
> Project: Hive
> Issue Type: Task
> Components: Query Planning
> Reporter: Sergio Peña
> Assignee: Sergio Peña
> Priority: Minor
>
> The Utilities class has two methods, {{getInputSummary}} and
> {{getInputPaths}}, that use the variable {{mapred.dfsclient.parallelism.max}}
> to get the summary of a list of input locations in parallel. These methods
> are Hive related, but the variable name does not look it is specific for Hive.
> Also, the above variable is not on HiveConf nor used anywhere else. I just
> found a reference on the Hadoop MR1 code.
> I'd like to propose the deprecation of {{mapred.dfsclient.parallelism.max}},
> and use a different variable name, such as
> {{hive.get.input.listing.num.threads}}, that reflects the intention of the
> variable. The removal of the old variable might happen on Hive 3.x
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