Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/11886#discussion_r57118942
--- Diff: core/src/main/scala/org/apache/spark/MapOutputTracker.scala ---
@@ -443,13 +443,12 @@ private[spark] class MapOutputTrackerMaster(conf:
SparkConf)
statuses = mapStatuses.getOrElse(shuffleId, Array[MapStatus]())
epochGotten = epoch
}
- }
- // If we got here, we failed to find the serialized locations in the
cache, so we pulled
- // out a snapshot of the locations as "statuses"; let's serialize and
return that
- val bytes = MapOutputTracker.serializeMapStatuses(statuses)
- logInfo("Size of output statuses for shuffle %d is %d
bytes".format(shuffleId, bytes.length))
- // Add them into the table only if the epoch hasn't changed while we
were working
- epochLock.synchronized {
+
+ // If we got here, we failed to find the serialized locations in the
cache, so we pulled
--- End diff --
OK, to paraphrase: everyone finds the cache is empty one by one very
quickly, and everyone proceeds to load the cached value. Isn't it simpler to
put this load in the `cachedSerializedStatuses.get(shuffleId) match ... None
=>` block then?
This code is pretty old but CC @mateiz or @JoshRosen in case they have an
opinion since they touched it last
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