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https://issues.apache.org/jira/browse/SPARK-4824?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Shixiong Zhu closed SPARK-4824.
-------------------------------
Resolution: Duplicate
> Join should use `Iterator` rather than `Iterable`
> -------------------------------------------------
>
> Key: SPARK-4824
> URL: https://issues.apache.org/jira/browse/SPARK-4824
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Reporter: Shixiong Zhu
>
> In Scala, `map` and `flatMap` of `Iterable` will copy the contents of
> `Iterable` to a new `Seq`. Such as,
> {code}
> val iterable = Seq(1, 2, 3).map(v => {
> println(v)
> v
> })
> println("Iterable map done")
> val iterator = Seq(1, 2, 3).iterator.map(v => {
> println(v)
> v
> })
> println("Iterator map done")
> {code}
> outputed
> {code}
> 1
> 2
> 3
> Iterable map done
> Iterator map done
> {code}
> So we should use 'iterator' to reduce memory consumed by join.
> Found by [~johannes.simon]
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