[jira] [Commented] (SPARK-38867) Avoid OOM when bufferedPlan has a lot of duplicate keys in SortMergeJoin codegen

["Apache Spark (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-38867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17521567#comment-17521567 ] 

Apache Spark commented on SPARK-38867:
--------------------------------------

User 'mcdull-zhang' has created a pull request for this issue:
https://github.com/apache/spark/pull/36178

> Avoid OOM when bufferedPlan has a lot of duplicate keys in SortMergeJoin codegen
> --------------------------------------------------------------------------------
>
>                 Key: SPARK-38867
>                 URL: https://issues.apache.org/jira/browse/SPARK-38867
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>    Affects Versions: 3.2.1
>            Reporter: mcdull_zhang
>            Priority: Minor
>
> WholeStageCodegenExec is wrapped in BufferedRowIterator.
> BufferedRowIterator uses a LinkedList to hold the output of WholeStageCodegenExec.
> When the parent of SortMergeJoin cannot codegen, SortMergeJoin needs to append the output to this LinkedList.
> SortMergeJoin processes a record in streamedPlan each time. If all records in bufferedPlan can match this record, all records in bufferedPlan will be saved in LinkedList, resulting in OOM.
> The above situation is very common in our internal use, so it is best to add a configuration to the codegen code. If there are enough pieces in the LinkedList, stop SortMergeJoin and let the parent consume it first.



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