Github user tgravescs commented on a diff in the pull request: https://github.com/apache/spark/pull/12113#discussion_r58536751 --- 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 + } + } + + // 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, bcast) = MapOutputTracker.serializeMapStatuses(statuses, broadcastManager, + isLocal, minSizeForBroadcast) + 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 + if (null != bcast) cachedSerializedBroadcast(shuffleId) = bcast + } else { + logInfo("Epoch changed, not caching!") + removeBroadcast(bcast) + } } + bytes } - bytes + newbytes } override def stop() { + mapOutputRequests.offer(PoisonPill) + threadpool.shutdown() sendTracker(StopMapOutputTracker) mapStatuses.clear() trackerEndpoint = null cachedSerializedStatuses.clear() + clearCachedBroadcast() --- End diff -- https://issues.apache.org/jira/browse/SPARK-14405
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