Mridul Muralidharan created SPARK-36892:
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             Summary: Disable batch fetch for a shuffle when push based shuffle 
is enabled
                 Key: SPARK-36892
                 URL: https://issues.apache.org/jira/browse/SPARK-36892
             Project: Spark
          Issue Type: Bug
          Components: Shuffle
    Affects Versions: 3.2.0
            Reporter: Mridul Muralidharan


When push based shuffle is enabled, efficient fetch of merged mapper shuffle 
output happens.
Unfortunately, this currently interacts badly with 
spark.sql.adaptive.fetchShuffleBlocksInBatch, potentially causing shuffle fetch 
to hang and/or duplicate data to be fetched, causing correctness issues.

Given batch fetch does not benefit spark stages reading merged blocks when push 
based shuffle is enabled, ShuffleBlockFetcherIterator.doBatchFetch can be 
disabled when push based shuffle is enabled.


Thx to [~Ngone51] for surfacing this issue.
+CC [~Gengliang.Wang]



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