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/*
* 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.scheduler
import java.nio.ByteBuffer
import java.util.{Locale, Timer, TimerTask}
import java.util.concurrent.{ConcurrentHashMap, TimeUnit}
import java.util.concurrent.atomic.AtomicLong
import scala.collection.Set
import scala.collection.mutable.{ArrayBuffer, HashMap, HashSet}
import scala.util.Random
import org.apache.spark._
import org.apache.spark.TaskState.TaskState
import org.apache.spark.internal.Logging
import org.apache.spark.internal.config
import org.apache.spark.rpc.RpcEndpoint
import org.apache.spark.scheduler.SchedulingMode.SchedulingMode
import org.apache.spark.scheduler.TaskLocality.TaskLocality
import org.apache.spark.storage.BlockManagerId
import org.apache.spark.util.{AccumulatorV2, SystemClock, ThreadUtils, Utils}
/**
* Schedules tasks for multiple types of clusters by acting through a SchedulerBackend.
* It can also work with a local setup by using a `LocalSchedulerBackend` and setting
* isLocal to true. It handles common logic, like determining a scheduling order across jobs, waking
* up to launch speculative tasks, etc.
*
* Clients should first call initialize() and start(), then submit task sets through the
* submitTasks method.
*
* THREADING: [[SchedulerBackend]]s and task-submitting clients can call this class from multiple
* threads, so it needs locks in public API methods to maintain its state. In addition, some
* [[SchedulerBackend]]s synchronize on themselves when they want to send events here, and then
* acquire a lock on us, so we need to make sure that we don't try to lock the backend while
* we are holding a lock on ourselves.
*/
private[spark] class TaskSchedulerImpl(
val sc: SparkContext,
val maxTaskFailures: Int,
isLocal: Boolean = false)
extends TaskScheduler with Logging {
import TaskSchedulerImpl._
def this(sc: SparkContext) = {
this(sc, sc.conf.get(config.MAX_TASK_FAILURES))
}
// Lazily initializing blacklistTrackerOpt to avoid getting empty ExecutorAllocationClient,
// because ExecutorAllocationClient is created after this TaskSchedulerImpl.
private[scheduler] lazy val blacklistTrackerOpt = maybeCreateBlacklistTracker(sc)
val conf = sc.conf
// How often to check for speculative tasks
val SPECULATION_INTERVAL_MS = conf.getTimeAsMs("spark.speculation.interval", "100ms")
// Duplicate copies of a task will only be launched if the original copy has been running for
// at least this amount of time. This is to avoid the overhead of launching speculative copies
// of tasks that are very short.
val MIN_TIME_TO_SPECULATION = 100
private val speculationScheduler =
ThreadUtils.newDaemonSingleThreadScheduledExecutor("task-scheduler-speculation")
// Threshold above which we warn user initial TaskSet may be starved
val STARVATION_TIMEOUT_MS = conf.getTimeAsMs("spark.starvation.timeout", "15s")
// CPUs to request per task
val CPUS_PER_TASK = conf.getInt("spark.task.cpus", 1)
// TaskSetManagers are not thread safe, so any access to one should be synchronized
// on this class.
private val taskSetsByStageIdAndAttempt = new HashMap[Int, HashMap[Int, TaskSetManager]]
// Protected by `this`
private[scheduler] val taskIdToTaskSetManager = new ConcurrentHashMap[Long, TaskSetManager]
val taskIdToExecutorId = new HashMap[Long, String]
@volatile private var hasReceivedTask = false
@volatile private var hasLaunchedTask = false
private val starvationTimer = new Timer(true)
// Incrementing task IDs
val nextTaskId = new AtomicLong(0)
// IDs of the tasks running on each executor
private val executorIdToRunningTaskIds = new HashMap[String, HashSet[Long]]
def runningTasksByExecutors: Map[String, Int] = synchronized {
executorIdToRunningTaskIds.toMap.mapValues(_.size)
}
// The set of executors we have on each host; this is used to compute hostsAlive, which
// in turn is used to decide when we can attain data locality on a given host
protected val hostToExecutors = new HashMap[String, HashSet[String]]
protected val hostsByRack = new HashMap[String, HashSet[String]]
protected val executorIdToHost = new HashMap[String, String]
private val abortTimer = new Timer(true)
private val clock = new SystemClock
// Exposed for testing
val unschedulableTaskSetToExpiryTime = new HashMap[TaskSetManager, Long]
// Listener object to pass upcalls into
var dagScheduler: DAGScheduler = null
var backend: SchedulerBackend = null
val mapOutputTracker = SparkEnv.get.mapOutputTracker.asInstanceOf[MapOutputTrackerMaster]
private var schedulableBuilder: SchedulableBuilder = null
// default scheduler is FIFO
private val schedulingModeConf = conf.get(SCHEDULER_MODE_PROPERTY, SchedulingMode.FIFO.toString)
val schedulingMode: SchedulingMode =
try {
SchedulingMode.withName(schedulingModeConf.toUpperCase(Locale.ROOT))
} catch {
case e: java.util.NoSuchElementException =>
throw new SparkException(s"Unrecognized $SCHEDULER_MODE_PROPERTY: $schedulingModeConf")
}
val rootPool: Pool = new Pool("", schedulingMode, 0, 0)
// This is a var so that we can reset it for testing purposes.
private[spark] var taskResultGetter = new TaskResultGetter(sc.env, this)
private lazy val barrierSyncTimeout = conf.get(config.BARRIER_SYNC_TIMEOUT)
private[scheduler] var barrierCoordinator: RpcEndpoint = null
private def maybeInitBarrierCoordinator(): Unit = {
if (barrierCoordinator == null) {
barrierCoordinator = new BarrierCoordinator(barrierSyncTimeout, sc.listenerBus,
sc.env.rpcEnv)
sc.env.rpcEnv.setupEndpoint("barrierSync", barrierCoordinator)
logInfo("Registered BarrierCoordinator endpoint")
}
}
override def setDAGScheduler(dagScheduler: DAGScheduler) {
this.dagScheduler = dagScheduler
}
def initialize(backend: SchedulerBackend) {
this.backend = backend
schedulableBuilder = {
schedulingMode match {
case SchedulingMode.FIFO =>
new FIFOSchedulableBuilder(rootPool)
case SchedulingMode.FAIR =>
new FairSchedulableBuilder(rootPool, conf)
case _ =>
throw new IllegalArgumentException(s"Unsupported $SCHEDULER_MODE_PROPERTY: " +
s"$schedulingMode")
}
}
schedulableBuilder.buildPools()
}
def newTaskId(): Long = nextTaskId.getAndIncrement()
override def start() {
backend.start()
if (!isLocal && conf.getBoolean("spark.speculation", false)) {
logInfo("Starting speculative execution thread")
speculationScheduler.scheduleWithFixedDelay(new Runnable {
override def run(): Unit = Utils.tryOrStopSparkContext(sc) {
checkSpeculatableTasks()
}
}, SPECULATION_INTERVAL_MS, SPECULATION_INTERVAL_MS, TimeUnit.MILLISECONDS)
}
}
override def postStartHook() {
waitBackendReady()
}
override def submitTasks(taskSet: TaskSet) {
val tasks = taskSet.tasks
logInfo("Adding task set " + taskSet.id + " with " + tasks.length + " tasks")
this.synchronized {
val manager = createTaskSetManager(taskSet, maxTaskFailures)
val stage = taskSet.stageId
val stageTaskSets =
taskSetsByStageIdAndAttempt.getOrElseUpdate(stage, new HashMap[Int, TaskSetManager])
// Mark all the existing TaskSetManagers of this stage as zombie, as we are adding a new one.
// This is necessary to handle a corner case. Let's say a stage has 10 partitions and has 2
// TaskSetManagers: TSM1(zombie) and TSM2(active). TSM1 has a running task for partition 10
// and it completes. TSM2 finishes tasks for partition 1-9, and thinks he is still active
// because partition 10 is not completed yet. However, DAGScheduler gets task completion
// events for all the 10 partitions and thinks the stage is finished. If it's a shuffle stage
// and somehow it has missing map outputs, then DAGScheduler will resubmit it and create a
// TSM3 for it. As a stage can't have more than one active task set managers, we must mark
// TSM2 as zombie (it actually is).
stageTaskSets.foreach { case (_, ts) =>
ts.isZombie = true
}
stageTaskSets(taskSet.stageAttemptId) = manager
schedulableBuilder.addTaskSetManager(manager, manager.taskSet.properties)
if (!isLocal && !hasReceivedTask) {
starvationTimer.scheduleAtFixedRate(new TimerTask() {
override def run() {
if (!hasLaunchedTask) {
logWarning("Initial job has not accepted any resources; " +
"check your cluster UI to ensure that workers are registered " +
"and have sufficient resources")
} else {
this.cancel()
}
}
}, STARVATION_TIMEOUT_MS, STARVATION_TIMEOUT_MS)
}
hasReceivedTask = true
}
backend.reviveOffers()
}
// Label as private[scheduler] to allow tests to swap in different task set managers if necessary
private[scheduler] def createTaskSetManager(
taskSet: TaskSet,
maxTaskFailures: Int): TaskSetManager = {
new TaskSetManager(this, taskSet, maxTaskFailures, blacklistTrackerOpt)
}
override def cancelTasks(stageId: Int, interruptThread: Boolean): Unit = synchronized {
logInfo("Cancelling stage " + stageId)
// Kill all running tasks for the stage.
killAllTaskAttempts(stageId, interruptThread, reason = "Stage cancelled")
// Cancel all attempts for the stage.
taskSetsByStageIdAndAttempt.get(stageId).foreach { attempts =>
attempts.foreach { case (_, tsm) =>
tsm.abort("Stage %s cancelled".format(stageId))
logInfo("Stage %d was cancelled".format(stageId))
}
}
}
override def killTaskAttempt(taskId: Long, interruptThread: Boolean, reason: String): Boolean = {
logInfo(s"Killing task $taskId: $reason")
val execId = taskIdToExecutorId.get(taskId)
if (execId.isDefined) {
backend.killTask(taskId, execId.get, interruptThread, reason)
true
} else {
logWarning(s"Could not kill task $taskId because no task with that ID was found.")
false
}
}
override def killAllTaskAttempts(
stageId: Int,
interruptThread: Boolean,
reason: String): Unit = synchronized {
logInfo(s"Killing all running tasks in stage $stageId: $reason")
taskSetsByStageIdAndAttempt.get(stageId).foreach { attempts =>
attempts.foreach { case (_, tsm) =>
// There are two possible cases here:
// 1. The task set manager has been created and some tasks have been scheduled.
// In this case, send a kill signal to the executors to kill the task.
// 2. The task set manager has been created but no tasks have been scheduled. In this case,
// simply continue.
tsm.runningTasksSet.foreach { tid =>
taskIdToExecutorId.get(tid).foreach { execId =>
backend.killTask(tid, execId, interruptThread, reason)
}
}
}
}
}
/**
* Called to indicate that all task attempts (including speculated tasks) associated with the
* given TaskSetManager have completed, so state associated with the TaskSetManager should be
* cleaned up.
*/
def taskSetFinished(manager: TaskSetManager): Unit = synchronized {
taskSetsByStageIdAndAttempt.get(manager.taskSet.stageId).foreach { taskSetsForStage =>
taskSetsForStage -= manager.taskSet.stageAttemptId
if (taskSetsForStage.isEmpty) {
taskSetsByStageIdAndAttempt -= manager.taskSet.stageId
}
}
manager.parent.removeSchedulable(manager)
logInfo(s"Removed TaskSet ${manager.taskSet.id}, whose tasks have all completed, from pool" +
s" ${manager.parent.name}")
}
private def resourceOfferSingleTaskSet(
taskSet: TaskSetManager,
maxLocality: TaskLocality,
shuffledOffers: Seq[WorkerOffer],
availableCpus: Array[Int],
tasks: IndexedSeq[ArrayBuffer[TaskDescription]],
addressesWithDescs: ArrayBuffer[(String, TaskDescription)]) : Boolean = {
var launchedTask = false
// nodes and executors that are blacklisted for the entire application have already been
// filtered out by this point
for (i <- 0 until shuffledOffers.size) {
val execId = shuffledOffers(i).executorId
val host = shuffledOffers(i).host
if (availableCpus(i) >= CPUS_PER_TASK) {
try {
for (task <- taskSet.resourceOffer(execId, host, maxLocality)) {
tasks(i) += task
val tid = task.taskId
taskIdToTaskSetManager.put(tid, taskSet)
taskIdToExecutorId(tid) = execId
executorIdToRunningTaskIds(execId).add(tid)
availableCpus(i) -= CPUS_PER_TASK
assert(availableCpus(i) >= 0)
// Only update hosts for a barrier task.
if (taskSet.isBarrier) {
// The executor address is expected to be non empty.
addressesWithDescs += (shuffledOffers(i).address.get -> task)
}
launchedTask = true
}
} catch {
case e: TaskNotSerializableException =>
logError(s"Resource offer failed, task set ${taskSet.name} was not serializable")
// Do not offer resources for this task, but don't throw an error to allow other
// task sets to be submitted.
return launchedTask
}
}
}
return launchedTask
}
/**
* Called by cluster manager to offer resources on slaves. We respond by asking our active task
* sets for tasks in order of priority. We fill each node with tasks in a round-robin manner so
* that tasks are balanced across the cluster.
*/
def resourceOffers(offers: IndexedSeq[WorkerOffer]): Seq[Seq[TaskDescription]] = synchronized {
// Mark each slave as alive and remember its hostname
// Also track if new executor is added
var newExecAvail = false
for (o <- offers) {
if (!hostToExecutors.contains(o.host)) {
hostToExecutors(o.host) = new HashSet[String]()
}
if (!executorIdToRunningTaskIds.contains(o.executorId)) {
hostToExecutors(o.host) += o.executorId
executorAdded(o.executorId, o.host)
executorIdToHost(o.executorId) = o.host
executorIdToRunningTaskIds(o.executorId) = HashSet[Long]()
newExecAvail = true
}
for (rack <- getRackForHost(o.host)) {
hostsByRack.getOrElseUpdate(rack, new HashSet[String]()) += o.host
}
}
// Before making any offers, remove any nodes from the blacklist whose blacklist has expired. Do
// this here to avoid a separate thread and added synchronization overhead, and also because
// updating the blacklist is only relevant when task offers are being made.
blacklistTrackerOpt.foreach(_.applyBlacklistTimeout())
val filteredOffers = blacklistTrackerOpt.map { blacklistTracker =>
offers.filter { offer =>
!blacklistTracker.isNodeBlacklisted(offer.host) &&
!blacklistTracker.isExecutorBlacklisted(offer.executorId)
}
}.getOrElse(offers)
val shuffledOffers = shuffleOffers(filteredOffers)
// Build a list of tasks to assign to each worker.
val tasks = shuffledOffers.map(o => new ArrayBuffer[TaskDescription](o.cores / CPUS_PER_TASK))
val availableCpus = shuffledOffers.map(o => o.cores).toArray
val sortedTaskSets = rootPool.getSortedTaskSetQueue
for (taskSet <- sortedTaskSets) {
logDebug("parentName: %s, name: %s, runningTasks: %s".format(
taskSet.parent.name, taskSet.name, taskSet.runningTasks))
if (newExecAvail) {
taskSet.executorAdded()
}
}
// Take each TaskSet in our scheduling order, and then offer it each node in increasing order
// of locality levels so that it gets a chance to launch local tasks on all of them.
// NOTE: the preferredLocality order: PROCESS_LOCAL, NODE_LOCAL, NO_PREF, RACK_LOCAL, ANY
for (taskSet <- sortedTaskSets) {
val availableSlots = availableCpus.map(c => c / CPUS_PER_TASK).sum
// Skip the barrier taskSet if the available slots are less than the number of pending tasks.
if (taskSet.isBarrier && availableSlots < taskSet.numTasks) {
// Skip the launch process.
// TODO SPARK-24819 If the job requires more slots than available (both busy and free
// slots), fail the job on submit.
logInfo(s"Skip current round of resource offers for barrier stage ${taskSet.stageId} " +
s"because the barrier taskSet requires ${taskSet.numTasks} slots, while the total " +
s"number of available slots is $availableSlots.")
} else {
var launchedAnyTask = false
// Record all the executor IDs assigned barrier tasks on.
val addressesWithDescs = ArrayBuffer[(String, TaskDescription)]()
for (currentMaxLocality <- taskSet.myLocalityLevels) {
var launchedTaskAtCurrentMaxLocality = false
do {
launchedTaskAtCurrentMaxLocality = resourceOfferSingleTaskSet(taskSet,
currentMaxLocality, shuffledOffers, availableCpus, tasks, addressesWithDescs)
launchedAnyTask |= launchedTaskAtCurrentMaxLocality
} while (launchedTaskAtCurrentMaxLocality)
}
if (!launchedAnyTask) {
taskSet.getCompletelyBlacklistedTaskIfAny(hostToExecutors).foreach { taskIndex =>
// If the taskSet is unschedulable we try to find an existing idle blacklisted
// executor. If we cannot find one, we abort immediately. Else we kill the idle
// executor and kick off an abortTimer which if it doesn't schedule a task within the
// the timeout will abort the taskSet if we were unable to schedule any task from the
// taskSet.
// Note 1: We keep track of schedulability on a per taskSet basis rather than on a per
// task basis.
// Note 2: The taskSet can still be aborted when there are more than one idle
// blacklisted executors and dynamic allocation is on. This can happen when a killed
// idle executor isn't replaced in time by ExecutorAllocationManager as it relies on
// pending tasks and doesn't kill executors on idle timeouts, resulting in the abort
// timer to expire and abort the taskSet.
executorIdToRunningTaskIds.find(x => !isExecutorBusy(x._1)) match {
case Some ((executorId, _)) =>
if (!unschedulableTaskSetToExpiryTime.contains(taskSet)) {
blacklistTrackerOpt.foreach(blt => blt.killBlacklistedIdleExecutor(executorId))
val timeout = conf.get(config.UNSCHEDULABLE_TASKSET_TIMEOUT) * 1000
unschedulableTaskSetToExpiryTime(taskSet) = clock.getTimeMillis() + timeout
logInfo(s"Waiting for $timeout ms for completely "
+ s"blacklisted task to be schedulable again before aborting $taskSet.")
abortTimer.schedule(
createUnschedulableTaskSetAbortTimer(taskSet, taskIndex), timeout)
}
case None => // Abort Immediately
logInfo("Cannot schedule any task because of complete blacklisting. No idle" +
s" executors can be found to kill. Aborting $taskSet." )
taskSet.abortSinceCompletelyBlacklisted(taskIndex)
}
}
} else {
// We want to defer killing any taskSets as long as we have a non blacklisted executor
// which can be used to schedule a task from any active taskSets. This ensures that the
// job can make progress.
// Note: It is theoretically possible that a taskSet never gets scheduled on a
// non-blacklisted executor and the abort timer doesn't kick in because of a constant
// submission of new TaskSets. See the PR for more details.
if (unschedulableTaskSetToExpiryTime.nonEmpty) {
logInfo("Clearing the expiry times for all unschedulable taskSets as a task was " +
"recently scheduled.")
unschedulableTaskSetToExpiryTime.clear()
}
}
if (launchedAnyTask && taskSet.isBarrier) {
// Check whether the barrier tasks are partially launched.
// TODO SPARK-24818 handle the assert failure case (that can happen when some locality
// requirements are not fulfilled, and we should revert the launched tasks).
require(addressesWithDescs.size == taskSet.numTasks,
s"Skip current round of resource offers for barrier stage ${taskSet.stageId} " +
s"because only ${addressesWithDescs.size} out of a total number of " +
s"${taskSet.numTasks} tasks got resource offers. The resource offers may have " +
"been blacklisted or cannot fulfill task locality requirements.")
// materialize the barrier coordinator.
maybeInitBarrierCoordinator()
// Update the taskInfos into all the barrier task properties.
val addressesStr = addressesWithDescs
// Addresses ordered by partitionId
.sortBy(_._2.partitionId)
.map(_._1)
.mkString(",")
addressesWithDescs.foreach(_._2.properties.setProperty("addresses", addressesStr))
logInfo(s"Successfully scheduled all the ${addressesWithDescs.size} tasks for barrier " +
s"stage ${taskSet.stageId}.")
}
}
}
// TODO SPARK-24823 Cancel a job that contains barrier stage(s) if the barrier tasks don't get
// launched within a configured time.
if (tasks.size > 0) {
hasLaunchedTask = true
}
return tasks
}
private def createUnschedulableTaskSetAbortTimer(
taskSet: TaskSetManager,
taskIndex: Int): TimerTask = {
new TimerTask() {
override def run() {
if (unschedulableTaskSetToExpiryTime.contains(taskSet) &&
unschedulableTaskSetToExpiryTime(taskSet) <= clock.getTimeMillis()) {
logInfo("Cannot schedule any task because of complete blacklisting. " +
s"Wait time for scheduling expired. Aborting $taskSet.")
taskSet.abortSinceCompletelyBlacklisted(taskIndex)
} else {
this.cancel()
}
}
}
}
/**
* Shuffle offers around to avoid always placing tasks on the same workers. Exposed to allow
* overriding in tests, so it can be deterministic.
*/
protected def shuffleOffers(offers: IndexedSeq[WorkerOffer]): IndexedSeq[WorkerOffer] = {
Random.shuffle(offers)
}
def statusUpdate(tid: Long, state: TaskState, serializedData: ByteBuffer) {
var failedExecutor: Option[String] = None
var reason: Option[ExecutorLossReason] = None
synchronized {
try {
Option(taskIdToTaskSetManager.get(tid)) match {
case Some(taskSet) =>
if (state == TaskState.LOST) {
// TaskState.LOST is only used by the deprecated Mesos fine-grained scheduling mode,
// where each executor corresponds to a single task, so mark the executor as failed.
val execId = taskIdToExecutorId.getOrElse(tid, throw new IllegalStateException(
"taskIdToTaskSetManager.contains(tid) <=> taskIdToExecutorId.contains(tid)"))
if (executorIdToRunningTaskIds.contains(execId)) {
reason = Some(
SlaveLost(s"Task $tid was lost, so marking the executor as lost as well."))
removeExecutor(execId, reason.get)
failedExecutor = Some(execId)
}
}
if (TaskState.isFinished(state)) {
cleanupTaskState(tid)
taskSet.removeRunningTask(tid)
if (state == TaskState.FINISHED) {
taskResultGetter.enqueueSuccessfulTask(taskSet, tid, serializedData)
} else if (Set(TaskState.FAILED, TaskState.KILLED, TaskState.LOST).contains(state)) {
taskResultGetter.enqueueFailedTask(taskSet, tid, state, serializedData)
}
}
case None =>
logError(
("Ignoring update with state %s for TID %s because its task set is gone (this is " +
"likely the result of receiving duplicate task finished status updates) or its " +
"executor has been marked as failed.")
.format(state, tid))
}
} catch {
case e: Exception => logError("Exception in statusUpdate", e)
}
}
// Update the DAGScheduler without holding a lock on this, since that can deadlock
if (failedExecutor.isDefined) {
assert(reason.isDefined)
dagScheduler.executorLost(failedExecutor.get, reason.get)
backend.reviveOffers()
}
}
/**
* Update metrics for in-progress tasks and let the master know that the BlockManager is still
* alive. Return true if the driver knows about the given block manager. Otherwise, return false,
* indicating that the block manager should re-register.
*/
override def executorHeartbeatReceived(
execId: String,
accumUpdates: Array[(Long, Seq[AccumulatorV2[_, _]])],
blockManagerId: BlockManagerId): Boolean = {
// (taskId, stageId, stageAttemptId, accumUpdates)
val accumUpdatesWithTaskIds: Array[(Long, Int, Int, Seq[AccumulableInfo])] = {
accumUpdates.flatMap { case (id, updates) =>
val accInfos = updates.map(acc => acc.toInfo(Some(acc.value), None))
Option(taskIdToTaskSetManager.get(id)).map { taskSetMgr =>
(id, taskSetMgr.stageId, taskSetMgr.taskSet.stageAttemptId, accInfos)
}
}
}
dagScheduler.executorHeartbeatReceived(execId, accumUpdatesWithTaskIds, blockManagerId)
}
def handleTaskGettingResult(taskSetManager: TaskSetManager, tid: Long): Unit = synchronized {
taskSetManager.handleTaskGettingResult(tid)
}
def handleSuccessfulTask(
taskSetManager: TaskSetManager,
tid: Long,
taskResult: DirectTaskResult[_]): Unit = synchronized {
taskSetManager.handleSuccessfulTask(tid, taskResult)
}
def handleFailedTask(
taskSetManager: TaskSetManager,
tid: Long,
taskState: TaskState,
reason: TaskFailedReason): Unit = synchronized {
taskSetManager.handleFailedTask(tid, taskState, reason)
if (!taskSetManager.isZombie && !taskSetManager.someAttemptSucceeded(tid)) {
// Need to revive offers again now that the task set manager state has been updated to
// reflect failed tasks that need to be re-run.
backend.reviveOffers()
}
}
def error(message: String) {
synchronized {
if (taskSetsByStageIdAndAttempt.nonEmpty) {
// Have each task set throw a SparkException with the error
for {
attempts <- taskSetsByStageIdAndAttempt.values
manager <- attempts.values
} {
try {
manager.abort(message)
} catch {
case e: Exception => logError("Exception in error callback", e)
}
}
} else {
// No task sets are active but we still got an error. Just exit since this
// must mean the error is during registration.
// It might be good to do something smarter here in the future.
throw new SparkException(s"Exiting due to error from cluster scheduler: $message")
}
}
}
override def stop() {
speculationScheduler.shutdown()
if (backend != null) {
backend.stop()
}
if (taskResultGetter != null) {
taskResultGetter.stop()
}
if (barrierCoordinator != null) {
barrierCoordinator.stop()
}
starvationTimer.cancel()
abortTimer.cancel()
}
override def defaultParallelism(): Int = backend.defaultParallelism()
// Check for speculatable tasks in all our active jobs.
def checkSpeculatableTasks() {
var shouldRevive = false
synchronized {
shouldRevive = rootPool.checkSpeculatableTasks(MIN_TIME_TO_SPECULATION)
}
if (shouldRevive) {
backend.reviveOffers()
}
}
override def executorLost(executorId: String, reason: ExecutorLossReason): Unit = {
var failedExecutor: Option[String] = None
synchronized {
if (executorIdToRunningTaskIds.contains(executorId)) {
val hostPort = executorIdToHost(executorId)
logExecutorLoss(executorId, hostPort, reason)
removeExecutor(executorId, reason)
failedExecutor = Some(executorId)
} else {
executorIdToHost.get(executorId) match {
case Some(hostPort) =>
// If the host mapping still exists, it means we don't know the loss reason for the
// executor. So call removeExecutor() to update tasks running on that executor when
// the real loss reason is finally known.
logExecutorLoss(executorId, hostPort, reason)
removeExecutor(executorId, reason)
case None =>
// We may get multiple executorLost() calls with different loss reasons. For example,
// one may be triggered by a dropped connection from the slave while another may be a
// report of executor termination from Mesos. We produce log messages for both so we
// eventually report the termination reason.
logError(s"Lost an executor $executorId (already removed): $reason")
}
}
}
// Call dagScheduler.executorLost without holding the lock on this to prevent deadlock
if (failedExecutor.isDefined) {
dagScheduler.executorLost(failedExecutor.get, reason)
backend.reviveOffers()
}
}
override def workerRemoved(workerId: String, host: String, message: String): Unit = {
logInfo(s"Handle removed worker $workerId: $message")
dagScheduler.workerRemoved(workerId, host, message)
}
private def logExecutorLoss(
executorId: String,
hostPort: String,
reason: ExecutorLossReason): Unit = reason match {
case LossReasonPending =>
logDebug(s"Executor $executorId on $hostPort lost, but reason not yet known.")
case ExecutorKilled =>
logInfo(s"Executor $executorId on $hostPort killed by driver.")
case _ =>
logError(s"Lost executor $executorId on $hostPort: $reason")
}
/**
* Cleans up the TaskScheduler's state for tracking the given task.
*/
private def cleanupTaskState(tid: Long): Unit = {
taskIdToTaskSetManager.remove(tid)
taskIdToExecutorId.remove(tid).foreach { executorId =>
executorIdToRunningTaskIds.get(executorId).foreach { _.remove(tid) }
}
}
/**
* Remove an executor from all our data structures and mark it as lost. If the executor's loss
* reason is not yet known, do not yet remove its association with its host nor update the status
* of any running tasks, since the loss reason defines whether we'll fail those tasks.
*/
private def removeExecutor(executorId: String, reason: ExecutorLossReason) {
// The tasks on the lost executor may not send any more status updates (because the executor
// has been lost), so they should be cleaned up here.
executorIdToRunningTaskIds.remove(executorId).foreach { taskIds =>
logDebug("Cleaning up TaskScheduler state for tasks " +
s"${taskIds.mkString("[", ",", "]")} on failed executor $executorId")
// We do not notify the TaskSetManager of the task failures because that will
// happen below in the rootPool.executorLost() call.
taskIds.foreach(cleanupTaskState)
}
val host = executorIdToHost(executorId)
val execs = hostToExecutors.getOrElse(host, new HashSet)
execs -= executorId
if (execs.isEmpty) {
hostToExecutors -= host
for (rack <- getRackForHost(host); hosts <- hostsByRack.get(rack)) {
hosts -= host
if (hosts.isEmpty) {
hostsByRack -= rack
}
}
}
if (reason != LossReasonPending) {
executorIdToHost -= executorId
rootPool.executorLost(executorId, host, reason)
}
blacklistTrackerOpt.foreach(_.handleRemovedExecutor(executorId))
}
def executorAdded(execId: String, host: String) {
dagScheduler.executorAdded(execId, host)
}
def getExecutorsAliveOnHost(host: String): Option[Set[String]] = synchronized {
hostToExecutors.get(host).map(_.toSet)
}
def hasExecutorsAliveOnHost(host: String): Boolean = synchronized {
hostToExecutors.contains(host)
}
def hasHostAliveOnRack(rack: String): Boolean = synchronized {
hostsByRack.contains(rack)
}
def isExecutorAlive(execId: String): Boolean = synchronized {
executorIdToRunningTaskIds.contains(execId)
}
def isExecutorBusy(execId: String): Boolean = synchronized {
executorIdToRunningTaskIds.get(execId).exists(_.nonEmpty)
}
/**
* Get a snapshot of the currently blacklisted nodes for the entire application. This is
* thread-safe -- it can be called without a lock on the TaskScheduler.
*/
def nodeBlacklist(): scala.collection.immutable.Set[String] = {
blacklistTrackerOpt.map(_.nodeBlacklist()).getOrElse(scala.collection.immutable.Set())
}
// By default, rack is unknown
def getRackForHost(value: String): Option[String] = None
private def waitBackendReady(): Unit = {
if (backend.isReady) {
return
}
while (!backend.isReady) {
// Might take a while for backend to be ready if it is waiting on resources.
if (sc.stopped.get) {
// For example: the master removes the application for some reason
throw new IllegalStateException("Spark context stopped while waiting for backend")
}
synchronized {
this.wait(100)
}
}
}
override def applicationId(): String = backend.applicationId()
override def applicationAttemptId(): Option[String] = backend.applicationAttemptId()
private[scheduler] def taskSetManagerForAttempt(
stageId: Int,
stageAttemptId: Int): Option[TaskSetManager] = {
for {
attempts <- taskSetsByStageIdAndAttempt.get(stageId)
manager <- attempts.get(stageAttemptId)
} yield {
manager
}
}
/**
* Marks the task has completed in all TaskSetManagers for the given stage.
*
* After stage failure and retry, there may be multiple TaskSetManagers for the stage.
* If an earlier attempt of a stage completes a task, we should ensure that the later attempts
* do not also submit those same tasks. That also means that a task completion from an earlier
* attempt can lead to the entire stage getting marked as successful.
*/
private[scheduler] def markPartitionCompletedInAllTaskSets(
stageId: Int,
partitionId: Int,
taskInfo: TaskInfo) = {
taskSetsByStageIdAndAttempt.getOrElse(stageId, Map()).values.foreach { tsm =>
tsm.markPartitionCompleted(partitionId, taskInfo)
}
}
}
private[spark] object TaskSchedulerImpl {
val SCHEDULER_MODE_PROPERTY = "spark.scheduler.mode"
/**
* Used to balance containers across hosts.
*
* Accepts a map of hosts to resource offers for that host, and returns a prioritized list of
* resource offers representing the order in which the offers should be used. The resource
* offers are ordered such that we'll allocate one container on each host before allocating a
* second container on any host, and so on, in order to reduce the damage if a host fails.
*
* For example, given {@literal }, {@literal } and
* {@literal }, returns {@literal [o1, o5, o4, o2, o6, o3]}.
*/
def prioritizeContainers[K, T] (map: HashMap[K, ArrayBuffer[T]]): List[T] = {
val _keyList = new ArrayBuffer[K](map.size)
_keyList ++= map.keys
// order keyList based on population of value in map
val keyList = _keyList.sortWith(
(left, right) => map(left).size > map(right).size
)
val retval = new ArrayBuffer[T](keyList.size * 2)
var index = 0
var found = true
while (found) {
found = false
for (key <- keyList) {
val containerList: ArrayBuffer[T] = map.getOrElse(key, null)
assert(containerList != null)
// Get the index'th entry for this host - if present
if (index < containerList.size) {
retval += containerList.apply(index)
found = true
}
}
index += 1
}
retval.toList
}
private def maybeCreateBlacklistTracker(sc: SparkContext): Option[BlacklistTracker] = {
if (BlacklistTracker.isBlacklistEnabled(sc.conf)) {
val executorAllocClient: Option[ExecutorAllocationClient] = sc.schedulerBackend match {
case b: ExecutorAllocationClient => Some(b)
case _ => None
}
Some(new BlacklistTracker(sc, executorAllocClient))
} else {
None
}
}
}
