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https://issues.apache.org/jira/browse/HIVE-19937?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16539149#comment-16539149
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Misha Dmitriev commented on HIVE-19937:
---------------------------------------
A few small comments about the last patch:
# In the new *Deserializer code, there are many lines looking like
'partitionDesc.setXXX(partitionDesc.getXXX())'. Such code looks quite
non-obvious, so it would be good to add comments there explaining that this is
done to intern possible duplicate strings.
# Looks like there is a typo: a method that's really a getter has the set...
name:
+ public Map<String, List<String>> setEventSourceColumnTypeMap() {
+ return eventSourceColumnTypeMap;
+ }
# Still would be good to publish a jxray report for the same test before and
after this change, to make sure that the problems are indeed fixed.
> Use BeanSerializer for MapWork to carry calls to String.intern
> --------------------------------------------------------------
>
> 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, HIVE-19937.2.patch,
> HIVE-19937.3.patch, report.html
>
>
> 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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