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https://issues.apache.org/jira/browse/HIVE-19937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16527015#comment-16527015
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Sahil Takiar commented on HIVE-19937:
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Thanks for the review Xuefu!
[[email protected]] could you take a quick look too, just want to make sure I
am doing this correctly. The high level explanation is that in Hive on Spark, a
single Spark executor (a single JVM) can run multiple Spark tasks in parallel.
Each task creates its own copy of {{JobConf}} (basically all the Hive
properties). This can cause significant overhead in the JVM, so this patch
basically interns all the entries in {{JobConf}}.
> Intern JobConf objects in Spark tasks
> -------------------------------------
>
> Key: HIVE-19937
> URL: https://issues.apache.org/jira/browse/HIVE-19937
> Project: Hive
> Issue Type: Improvement
> Components: Spark
> Reporter: Sahil Takiar
> Assignee: Sahil Takiar
> Priority: Major
> Attachments: HIVE-19937.1.patch
>
>
> When fixing HIVE-16395, we decided that each new Spark task should clone the
> {{JobConf}} object to prevent any {{ConcurrentModificationException}} from
> being thrown. However, setting this variable comes at a cost of storing a
> duplicate {{JobConf}} object for each Spark task. These objects can take up a
> significant amount of memory, we should intern them so that Spark tasks
> running in the same JVM don't store duplicate copies.
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