karuppayya commented on code in PR #52606:
URL: https://github.com/apache/spark/pull/52606#discussion_r2450018432
##########
core/src/main/scala/org/apache/spark/storage/BlockManagerStorageEndpoint.scala:
##########
@@ -57,7 +57,14 @@ class BlockManagerStorageEndpoint(
case RemoveShuffle(shuffleId) =>
doAsync[Boolean](log"removing shuffle ${MDC(SHUFFLE_ID, shuffleId)}",
context) {
- if (mapOutputTracker != null) {
+ if (mapOutputTracker != null &&
!mapOutputTracker.isInstanceOf[MapOutputTrackerMaster]) {
+ // SPARK-53898: `MapOutputTrackerMaster.unregisterShuffle()` should
only be called
+ // through `ContextCleaner` when the shuffle is considered no longer
referenced anywhere.
+ // Otherwise, we might hit exceptions if there is any subsequent
access (which still
+ // reference that shuffle) to that shuffle metadata in
`MapOutputTrackerMaster`. E.g.,
+ // an ongoing subquery could access the same shuffle metadata which
could have been
+ // cleaned up after the main query completes. Note this currently
only happens in local
+ // cluster where both driver and executor use the
`MapOutputTrackerMaster`.
mapOutputTracker.unregisterShuffle(shuffleId)
Review Comment:
On executors, it would call the
[MapOutputTrackerWorker#unregisterShuffle](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/MapOutputTracker.scala#L1526),
where the shuffle status are not cleaned up unlike in
[MapOutputTrackerMaster#unregisterShuffle](https://github.com/apache/spark/blob/master/core/src/main/scala/org/apache/spark/MapOutputTracker.scala#L946)
In local, we just have MapoutputTrackerMaster and ends up cleaning the
shufflestatuses
MapOutputTrackerMaster
```
def unregisterShuffle(shuffleId: Int): Unit = {
shuffleStatuses.remove(shuffleId).foreach { shuffleStatus =>
shuffleStatus.invalidateSerializedMapOutputStatusCache()
shuffleStatus.invalidateSerializedMergeOutputStatusCache()
}
}
```
MapOutputTrackerWorker
```
def unregisterShuffle(shuffleId: Int): Unit = {
mapStatuses.remove(shuffleId)
mergeStatuses.remove(shuffleId)
shufflePushMergerLocations.remove(shuffleId)
}
```
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