Github user vanzin commented on a diff in the pull request:
https://github.com/apache/spark/pull/19041#discussion_r143814023
--- Diff: core/src/main/scala/org/apache/spark/CacheRecoveryManager.scala
---
@@ -0,0 +1,250 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark
+
+import java.util.concurrent.{ScheduledFuture, TimeUnit}
+
+import scala.collection.mutable
+import scala.concurrent.{ExecutionContext, Future}
+import scala.util.Failure
+
+import org.apache.spark.internal.Logging
+import
org.apache.spark.internal.config.DYN_ALLOCATION_RECOVER_CACHE_TIMEOUT
+import org.apache.spark.rpc.RpcEndpointRef
+import org.apache.spark.storage.{BlockId, BlockManagerId, RDDBlockId}
+import org.apache.spark.storage.BlockManagerMessages.{GetCachedBlocks,
GetMemoryStatus, GetSizeOfBlocks, ReplicateOneBlock}
+import org.apache.spark.util.ThreadUtils
+
+/**
+ * Responsible for asynchronously replicating all of an executors cached
blocks, and then shutting
+ * it down.
+ */
+final private class CacheRecoveryManager(
+ state: CacheRecoveryManagerState,
+ conf: SparkConf)
+ extends Logging {
+
+ private val threadPool =
ThreadUtils.newDaemonCachedThreadPool("recover-cache-shutdown-pool")
+ private implicit val asyncExecutionContext: ExecutionContext =
+ ExecutionContext.fromExecutorService(threadPool)
+
+ /**
+ * Start the recover cache shutdown process for these executors
+ *
+ * @param execIds the executors to start shutting down
+ */
+ def startExecutorKill(execIds: Seq[String]): Unit = {
+ logDebug(s"Recover cached data before shutting down executors
${execIds.mkString(", ")}.")
+ checkForReplicableBlocks(execIds)
+ }
+
+ /**
+ * Stops all thread pools
+ *
+ * @return
+ */
+ def stop(): java.util.List[Runnable] = {
+ threadPool.shutdownNow()
+ state.stop()
+ }
+
+ /**
+ * Get list of cached blocks from BlockManagerMaster. If there are
cached blocks, replicate them,
+ * otherwise kill the executors
+ *
+ * @param execIds the executors to check
+ */
+ private def checkForReplicableBlocks(execIds: Seq[String]) =
state.getBlocks(execIds).foreach {
+ case (executorId, HasCachedBlocks) => replicateBlocks(executorId)
+ case (executorId, NoMoreBlocks | NotEnoughMemory) =>
state.killExecutor(executorId)
+ }
+
+ /**
+ * Replicate one cached block on an executor. If there are more, repeat.
If there are none, check
+ * with the block manager master again. If there is an error, go ahead
and kill executor.
+ *
+ * @param execId the executor to save a block one
+ */
+ private def replicateBlocks(execId: String): Unit = {
+ import scala.util.Success
+ val (response, blockId) = state.replicateFirstBlock(execId)
+ response.onComplete {
+ case Success(true) =>
+ logTrace(s"Finished replicating block
${blockId.getOrElse("unknown")} on exec $execId.")
+ replicateBlocks(execId)
+ case Success(false) =>
+ checkForReplicableBlocks(Seq(execId))
+ case Failure(f) =>
+ logWarning(s"Error trying to replicate block
${blockId.getOrElse("unknown")}.", f)
+ state.killExecutor(execId)
+ }
+ }
+}
+
+private object CacheRecoveryManager {
+ def apply(eam: ExecutorAllocationManager, conf: SparkConf):
CacheRecoveryManager = {
+ val bmme = SparkEnv.get.blockManager.master.driverEndpoint
+ val state = new CacheRecoveryManagerState(bmme, eam, conf)
+ new CacheRecoveryManager(state, conf)
+ }
+}
+
+/**
+ * Private class that holds state for all the executors being shutdown.
+ *
+ * @param blockManagerMasterEndpoint blockManagerMasterEndpoint
+ * @param executorAllocationManager ExecutorAllocationManager
+ * @param conf spark conf
+ */
+final private class CacheRecoveryManagerState(
+ blockManagerMasterEndpoint: RpcEndpointRef,
+ executorAllocationManager: ExecutorAllocationManager,
+ conf: SparkConf
+ ) extends Logging {
+
+ private val forceKillAfterS =
conf.get(DYN_ALLOCATION_RECOVER_CACHE_TIMEOUT)
+ private val scheduler =
+
ThreadUtils.newDaemonSingleThreadScheduledExecutor("recover-cache-shutdown-timers")
+
+ private val blocksToSave = new mutable.HashMap[String,
mutable.PriorityQueue[RDDBlockId]]
+ private val savedBlocks = new mutable.HashMap[String,
mutable.HashSet[RDDBlockId]]
+ private val killTimers = new mutable.HashMap[String,
ScheduledFuture[_]]
+
+ /**
+ * Query Block Manager Master for cached blocks.
+ *
+ * @param execIds the executors to query
+ * @return a map of executorId to its replication state.
+ */
+ def getBlocks(execIds: Seq[String]): Map[String,
ExecutorReplicationState] = synchronized {
+ val isThereEnoughMemory = checkFreeMem(execIds)
+
+ isThereEnoughMemory.map {
+ case (execId, true) =>
+ updateBlockState(execId)
+ val blocksRemain = blocksToSave.get(execId).exists(_.nonEmpty)
+ execId -> (if (blocksRemain) HasCachedBlocks else NoMoreBlocks)
+ case (execId, false) =>
+ execId -> NotEnoughMemory
+ }
+ }
+
+ /**
+ * Checks to see if there is enough memory on the cluster to hold the
cached blocks on these
+ * executors. Checks on a per executor basis from the smallest to the
largest.
+ *
+ * @param execIds the executors to query
+ * @return a map of executor ids to whether or not there is enough free
memory for them.
+ */
+ private def checkFreeMem(execIds: Seq[String]): Map[String, Boolean] = {
+ val execIdsToShutDown = execIds.toSet
+ val allExecMemStatus: Map[String, (Long, Long)] =
blockManagerMasterEndpoint
+ .askSync[Map[BlockManagerId, (Long, Long)]](GetMemoryStatus)
+ .map { case (blockManagerId, mem) => blockManagerId.executorId ->
mem }
+
+ val (expiringMemStatus, remainingMemStatus) =
allExecMemStatus.partition {
+ case (k, v) => execIdsToShutDown.contains(k)
+ }
+ val freeMemOnRemaining = remainingMemStatus.values.map(_._2).sum
+
+ val alreadyReplicatedBlocks: Map[String, Set[RDDBlockId]] =
+ savedBlocks.filterKeys(execIdsToShutDown).map { case (k, v) => k ->
v.toSet }.toMap
+
+ val getSizes = GetSizeOfBlocks(alreadyReplicatedBlocks)
+ val alreadyReplicatedBytes =
blockManagerMasterEndpoint.askSync[Map[String, Long]](getSizes)
+
+ val bytesToReplicate: Seq[(String, Long)] =
+ expiringMemStatus.map { case (execId, (maxMem, remainingMem)) =>
+ val alreadyReplicated = alreadyReplicatedBytes.getOrElse(execId,
0L)
+ val usedMem = maxMem - remainingMem
+ val toBeReplicatedMem = usedMem - alreadyReplicated
+ execId -> toBeReplicatedMem
+ }.toSeq.sortBy { case (k, v) => v }
+
+ bytesToReplicate.scan(("start", freeMemOnRemaining)) {
+ case ((_, remainingMem), (execId, mem)) => (execId, remainingMem -
mem)
+ }.drop(1)
+ .toMap
+ .mapValues(freeMem => freeMem >= 0)
+ }
+
+ /**
+ * Gets a list of cached blocks from the block manager master and
updates.
+ * CacheRecoveryManagerState.
+ *
+ * @param execId an executor Id
+ */
+ private def updateBlockState(execId: String): Unit = {
+ val blocks: mutable.Set[RDDBlockId] = blockManagerMasterEndpoint
+ .askSync[collection.Set[BlockId]](GetCachedBlocks(execId))
+ .flatMap(_.asRDDId)(collection.breakOut)
+
+ blocks --= savedBlocks.getOrElse(execId, new mutable.HashSet)
+ blocksToSave(execId) = mutable.PriorityQueue[RDDBlockId](blocks.toSeq:
_*)(Ordering.by(_.rddId))
+ killTimers.getOrElseUpdate(execId, scheduleKill(new
KillRunner(execId)))
+ }
+
+ class KillRunner(execId: String) extends Runnable { def run(): Unit =
killExecutor(execId) }
+ private def scheduleKill(k: KillRunner) = scheduler.schedule(k,
forceKillAfterS, TimeUnit.SECONDS)
+
+ /**
+ * Ask block manager master to replicate one cached block.
+ *
+ * @param execId the executor to replicate a block from
+ * @return false if there are no more blocks or if there is an issue
+ */
+ def replicateFirstBlock(execId: String): (Future[Boolean],
Option[RDDBlockId]) = synchronized {
+ logDebug(s"Replicate block on executor $execId.")
+ blocksToSave.get(execId) match {
+ case Some(p) if p.nonEmpty => doReplication(execId, p.dequeue())
+ case _ => (Future.successful(false), None)
+ }
+ }
+
+ private def doReplication(
+ execId: String,
+ blockId: RDDBlockId): (Future[Boolean], Option[RDDBlockId]) = {
+ val savedBlocksForExecutor = savedBlocks.getOrElseUpdate(execId, new
mutable.HashSet)
+ savedBlocksForExecutor += blockId
+ val replicateMessage = ReplicateOneBlock(execId, blockId,
blocksToSave.keys.toSeq)
+ logTrace(s"Started replicating block $blockId on exec $execId.")
+ val future = blockManagerMasterEndpoint.ask[Boolean](replicateMessage)
+ (future, Some(blockId))
+ }
+
+ /**
+ * Ask ExecutorAllocationManager to kill executor and clean up state
+ * Note executorAllocationManger.killExecutors is blocking, this
function should be fixed
+ * to use a non blocking version
+ * @param execId the executor to kill
+ */
+ def killExecutor(execId: String): Unit = synchronized {
+ logDebug(s"Send request to kill executor $execId.")
+ killTimers.remove(execId).foreach(_.cancel(false))
+ blocksToSave -= execId
+ savedBlocks -= execId
+ executorAllocationManager.killExecutors(Seq(execId), forceIfPending =
true)
+ }
+
+ def stop(): java.util.List[Runnable] = scheduler.shutdownNow()
--- End diff --
Same thing, don't see you using the return value anywhere, so `Unit`.
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