[jira] [Created] (SPARK-43043) Improve the performance of MapOutputTracker.updateMapOutput

["Xingbo Jiang (Jira)" <ji...@apache.org>]

Xingbo Jiang created SPARK-43043:
------------------------------------

             Summary: Improve the performance of MapOutputTracker.updateMapOutput
                 Key: SPARK-43043
                 URL: https://issues.apache.org/jira/browse/SPARK-43043
             Project: Spark
          Issue Type: Improvement
          Components: Spark Core
    Affects Versions: 3.3.2
            Reporter: Xingbo Jiang


Inside of MapOutputTracker, there is a line of code which does a linear find through a mapStatuses collection: https://github.com/apache/spark/blob/cb48c0e48eeff2b7b51176d0241491300e5aad6f/core/src/main/scala/org/apache/spark/MapOutputTracker.scala#L167  (plus a similar search a few lines down at https://github.com/apache/spark/blob/cb48c0e48eeff2b7b51176d0241491300e5aad6f/core/src/main/scala/org/apache/spark/MapOutputTracker.scala#L174)

This scan is necessary because we only know the mapId of the updated status and not its mapPartitionId.

We perform this scan once per migrated block, so if a large proportion of all blocks in the map are migrated then we get O(n^2) total runtime across all of the calls.

I think we might be able to fix this by extending ShuffleStatus to have an OpenHashMap mapping from mapId to mapPartitionId. 



--
This message was sent by Atlassian Jira
(v8.20.10#820010)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org