[GitHub] [spark] holdenk commented on a change in pull request #26017: [SPARK-29351][CORE] Avoid Full Synchronization in ShuffleMapStage

[GitBox <gi...@apache.org>]

holdenk commented on a change in pull request #26017: [SPARK-29351][CORE] Avoid Full Synchronization in ShuffleMapStage
URL: https://github.com/apache/spark/pull/26017#discussion_r331257348
 
 

 ##########
 File path: core/src/main/scala/org/apache/spark/MapOutputTracker.scala
 ##########
 @@ -169,33 +192,46 @@ private class ShuffleStatus(numPartitions: Int) {
   def serializedMapStatus(
       broadcastManager: BroadcastManager,
       isLocal: Boolean,
-      minBroadcastSize: Int): Array[Byte] = synchronized {
-    if (cachedSerializedMapStatus eq null) {
-      val serResult = MapOutputTracker.serializeMapStatuses(
+      minBroadcastSize: Int): Array[Byte] = {
+    var result: Array[Byte] = null
+
+    withReadLock {
 
 Review comment:
   This is the part where we expect the largest decrease in lock contention right?

----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
 
For queries about this service, please contact Infrastructure at:
users@infra.apache.org


With regards,
Apache Git Services

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