Github user tgravescs commented on a diff in the pull request:
https://github.com/apache/spark/pull/12113#discussion_r58267242
--- Diff: core/src/main/scala/org/apache/spark/MapOutputTracker.scala ---
@@ -428,40 +503,93 @@ private[spark] class MapOutputTrackerMaster(conf:
SparkConf)
}
}
+ private def removeBroadcast(bcast: Broadcast[_]): Unit = {
+ if (null != bcast) {
+ broadcastManager.unbroadcast(bcast.id,
+ removeFromDriver = true, blocking = false)
+ }
+ }
+
+ private def clearCachedBroadcast(): Unit = {
+ for (cached <- cachedSerializedBroadcast) removeBroadcast(cached._2)
+ cachedSerializedBroadcast.clear()
+ }
+
def getSerializedMapOutputStatuses(shuffleId: Int): Array[Byte] = {
var statuses: Array[MapStatus] = null
var epochGotten: Long = -1
epochLock.synchronized {
if (epoch > cacheEpoch) {
cachedSerializedStatuses.clear()
+ clearCachedBroadcast()
cacheEpoch = epoch
}
cachedSerializedStatuses.get(shuffleId) match {
case Some(bytes) =>
return bytes
case None =>
+ logDebug("cached status not found for : " + shuffleId)
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 (epoch == epochGotten) {
- cachedSerializedStatuses(shuffleId) = bytes
+
+ var shuffleIdLock = shuffleIdLocks.get(shuffleId)
+ if (null == shuffleIdLock) {
+ val newLock = new Object()
+ // in general, this condition should be false - but good to be
paranoid
+ val prevLock = shuffleIdLocks.putIfAbsent(shuffleId, newLock)
+ shuffleIdLock = if (null != prevLock) prevLock else newLock
+ }
+ val newbytes = shuffleIdLock.synchronized {
+
+ // double check to make sure someone else didn't serialize and cache
the same
+ // mapstatus while we were waiting on the synchronize
+ epochLock.synchronized {
+ if (epoch > cacheEpoch) {
+ cachedSerializedStatuses.clear()
+ clearCachedBroadcast()
+ cacheEpoch = epoch
+ }
+ cachedSerializedStatuses.get(shuffleId) match {
+ case Some(bytes) =>
+ return bytes
+ case None =>
+ logDebug("shuffle lock cached status not found for : " +
shuffleId)
+ statuses = mapStatuses.getOrElse(shuffleId, Array[MapStatus]())
+ epochGotten = epoch
+ }
+ }
--- End diff --
yeah good idea, I had started to but since it returns inside it makes it a
bit more complex and I forgot to get back to it.
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