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Bugfixes/improvements to scheduler
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Move the PR#517 of apache-incubator-spark to the apache-spark

Author: Mridul Muralidharan <[email protected]>

Closes #159 from mridulm/master and squashes the following commits:

5ff59c2 [Mridul Muralidharan] Change property in suite also
167fad8 [Mridul Muralidharan] Address review comments
9bda70e [Mridul Muralidharan] Address review comments, akwats add to failedExecutors
270d841 [Mridul Muralidharan] Address review comments
fa5d9f1 [Mridul Muralidharan] Bugfixes/improvements to scheduler : PR #517
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@mridulm @mateiz
mridulm authored and mateiz committed Mar 19, 2014
1 parent 6112270 commit ab747d3
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Showing 3 changed files with 152 additions and 20 deletions.
3 changes: 2 additions & 1 deletion core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -235,7 +235,8 @@ private[spark] class TaskSchedulerImpl(
taskIdToExecutorId(tid) = execId
activeExecutorIds += execId
executorsByHost(host) += execId
availableCpus(i) -= 1
availableCpus(i) -= taskSet.CPUS_PER_TASK
assert (availableCpus(i) >= 0)
launchedTask = true
}
}
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82 changes: 63 additions & 19 deletions core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,15 @@ private[spark] class TaskSetManager(
// CPUs to request per task
val CPUS_PER_TASK = conf.getInt("spark.task.cpus", 1)

/*
* Sometimes if an executor is dead or in an otherwise invalid state, the driver
* does not realize right away leading to repeated task failures. If enabled,
* this temporarily prevents a task from re-launching on an executor where
* it just failed.
*/
private val EXECUTOR_TASK_BLACKLIST_TIMEOUT =
conf.getLong("spark.scheduler.executorTaskBlacklistTime", 0L)

// Quantile of tasks at which to start speculation
val SPECULATION_QUANTILE = conf.getDouble("spark.speculation.quantile", 0.75)
val SPECULATION_MULTIPLIER = conf.getDouble("spark.speculation.multiplier", 1.5)
Expand All @@ -71,7 +80,9 @@ private[spark] class TaskSetManager(
val numTasks = tasks.length
val copiesRunning = new Array[Int](numTasks)
val successful = new Array[Boolean](numTasks)
val numFailures = new Array[Int](numTasks)
private val numFailures = new Array[Int](numTasks)
// key is taskId, value is a Map of executor id to when it failed
private val failedExecutors = new HashMap[Int, HashMap[String, Long]]()
val taskAttempts = Array.fill[List[TaskInfo]](numTasks)(Nil)
var tasksSuccessful = 0

Expand Down Expand Up @@ -228,12 +239,18 @@ private[spark] class TaskSetManager(
* This method also cleans up any tasks in the list that have already
* been launched, since we want that to happen lazily.
*/
private def findTaskFromList(list: ArrayBuffer[Int]): Option[Int] = {
while (!list.isEmpty) {
val index = list.last
list.trimEnd(1)
if (copiesRunning(index) == 0 && !successful(index)) {
return Some(index)
private def findTaskFromList(execId: String, list: ArrayBuffer[Int]): Option[Int] = {
var indexOffset = list.size

while (indexOffset > 0) {
indexOffset -= 1
val index = list(indexOffset)
if (!executorIsBlacklisted(execId, index)) {
// This should almost always be list.trimEnd(1) to remove tail
list.remove(indexOffset)
if (copiesRunning(index) == 0 && !successful(index)) {
return Some(index)
}
}
}
None
Expand All @@ -244,6 +261,21 @@ private[spark] class TaskSetManager(
taskAttempts(taskIndex).exists(_.host == host)
}

/**
* Is this re-execution of a failed task on an executor it already failed in before
* EXECUTOR_TASK_BLACKLIST_TIMEOUT has elapsed ?
*/
private def executorIsBlacklisted(execId: String, taskId: Int): Boolean = {
if (failedExecutors.contains(taskId)) {
val failed = failedExecutors.get(taskId).get

return failed.contains(execId) &&
clock.getTime() - failed.get(execId).get < EXECUTOR_TASK_BLACKLIST_TIMEOUT
}

false
}

/**
* Return a speculative task for a given executor if any are available. The task should not have
* an attempt running on this host, in case the host is slow. In addition, the task should meet
Expand All @@ -254,10 +286,13 @@ private[spark] class TaskSetManager(
{
speculatableTasks.retain(index => !successful(index)) // Remove finished tasks from set

def canRunOnHost(index: Int): Boolean =
!hasAttemptOnHost(index, host) && !executorIsBlacklisted(execId, index)

if (!speculatableTasks.isEmpty) {
// Check for process-local or preference-less tasks; note that tasks can be process-local
// on multiple nodes when we replicate cached blocks, as in Spark Streaming
for (index <- speculatableTasks if !hasAttemptOnHost(index, host)) {
for (index <- speculatableTasks if canRunOnHost(index)) {
val prefs = tasks(index).preferredLocations
val executors = prefs.flatMap(_.executorId)
if (prefs.size == 0 || executors.contains(execId)) {
Expand All @@ -268,7 +303,7 @@ private[spark] class TaskSetManager(

// Check for node-local tasks
if (TaskLocality.isAllowed(locality, TaskLocality.NODE_LOCAL)) {
for (index <- speculatableTasks if !hasAttemptOnHost(index, host)) {
for (index <- speculatableTasks if canRunOnHost(index)) {
val locations = tasks(index).preferredLocations.map(_.host)
if (locations.contains(host)) {
speculatableTasks -= index
Expand All @@ -280,7 +315,7 @@ private[spark] class TaskSetManager(
// Check for rack-local tasks
if (TaskLocality.isAllowed(locality, TaskLocality.RACK_LOCAL)) {
for (rack <- sched.getRackForHost(host)) {
for (index <- speculatableTasks if !hasAttemptOnHost(index, host)) {
for (index <- speculatableTasks if canRunOnHost(index)) {
val racks = tasks(index).preferredLocations.map(_.host).map(sched.getRackForHost)
if (racks.contains(rack)) {
speculatableTasks -= index
Expand All @@ -292,7 +327,7 @@ private[spark] class TaskSetManager(

// Check for non-local tasks
if (TaskLocality.isAllowed(locality, TaskLocality.ANY)) {
for (index <- speculatableTasks if !hasAttemptOnHost(index, host)) {
for (index <- speculatableTasks if canRunOnHost(index)) {
speculatableTasks -= index
return Some((index, TaskLocality.ANY))
}
Expand All @@ -309,32 +344,32 @@ private[spark] class TaskSetManager(
private def findTask(execId: String, host: String, locality: TaskLocality.Value)
: Option[(Int, TaskLocality.Value)] =
{
for (index <- findTaskFromList(getPendingTasksForExecutor(execId))) {
for (index <- findTaskFromList(execId, getPendingTasksForExecutor(execId))) {
return Some((index, TaskLocality.PROCESS_LOCAL))
}

if (TaskLocality.isAllowed(locality, TaskLocality.NODE_LOCAL)) {
for (index <- findTaskFromList(getPendingTasksForHost(host))) {
for (index <- findTaskFromList(execId, getPendingTasksForHost(host))) {
return Some((index, TaskLocality.NODE_LOCAL))
}
}

if (TaskLocality.isAllowed(locality, TaskLocality.RACK_LOCAL)) {
for {
rack <- sched.getRackForHost(host)
index <- findTaskFromList(getPendingTasksForRack(rack))
index <- findTaskFromList(execId, getPendingTasksForRack(rack))
} {
return Some((index, TaskLocality.RACK_LOCAL))
}
}

// Look for no-pref tasks after rack-local tasks since they can run anywhere.
for (index <- findTaskFromList(pendingTasksWithNoPrefs)) {
for (index <- findTaskFromList(execId, pendingTasksWithNoPrefs)) {
return Some((index, TaskLocality.PROCESS_LOCAL))
}

if (TaskLocality.isAllowed(locality, TaskLocality.ANY)) {
for (index <- findTaskFromList(allPendingTasks)) {
for (index <- findTaskFromList(execId, allPendingTasks)) {
return Some((index, TaskLocality.ANY))
}
}
Expand Down Expand Up @@ -460,6 +495,7 @@ private[spark] class TaskSetManager(
logInfo("Ignorning task-finished event for TID " + tid + " because task " +
index + " has already completed successfully")
}
failedExecutors.remove(index)
maybeFinishTaskSet()
}

Expand All @@ -480,17 +516,19 @@ private[spark] class TaskSetManager(
logWarning("Lost TID %s (task %s:%d)".format(tid, taskSet.id, index))
}
var taskMetrics : TaskMetrics = null
var failureReason = "unknown"
var failureReason: String = null
reason match {
case fetchFailed: FetchFailed =>
logWarning("Loss was due to fetch failure from " + fetchFailed.bmAddress)
if (!successful(index)) {
successful(index) = true
tasksSuccessful += 1
}
// Not adding to failed executors for FetchFailed.
isZombie = true

case TaskKilled =>
// Not adding to failed executors for TaskKilled.
logWarning("Task %d was killed.".format(tid))

case ef: ExceptionFailure =>
Expand All @@ -504,7 +542,8 @@ private[spark] class TaskSetManager(
return
}
val key = ef.description
failureReason = "Exception failure: %s".format(ef.description)
failureReason = "Exception failure in TID %s on host %s: %s".format(
tid, info.host, ef.description)
val now = clock.getTime()
val (printFull, dupCount) = {
if (recentExceptions.contains(key)) {
Expand Down Expand Up @@ -533,11 +572,16 @@ private[spark] class TaskSetManager(
failureReason = "Lost result for TID %s on host %s".format(tid, info.host)
logWarning(failureReason)

case _ => {}
case _ =>
failureReason = "TID %s on host %s failed for unknown reason".format(tid, info.host)
}
// always add to failed executors
failedExecutors.getOrElseUpdate(index, new HashMap[String, Long]()).
put(info.executorId, clock.getTime())
sched.dagScheduler.taskEnded(tasks(index), reason, null, null, info, taskMetrics)
addPendingTask(index)
if (!isZombie && state != TaskState.KILLED) {
assert (null != failureReason)
numFailures(index) += 1
if (numFailures(index) >= maxTaskFailures) {
logError("Task %s:%d failed %d times; aborting job".format(
Expand Down
87 changes: 87 additions & 0 deletions core/src/test/scala/org/apache/spark/scheduler/TaskSetManagerSuite.scala
View file
Original file line number Diff line number Diff line change
Expand Up @@ -298,6 +298,93 @@ class TaskSetManagerSuite extends FunSuite with LocalSparkContext with Logging {
}
}

test("executors should be blacklisted after task failure, in spite of locality preferences") {
val rescheduleDelay = 300L
val conf = new SparkConf().
set("spark.scheduler.executorTaskBlacklistTime", rescheduleDelay.toString).
// dont wait to jump locality levels in this test
set("spark.locality.wait", "0")

sc = new SparkContext("local", "test", conf)
// two executors on same host, one on different.
val sched = new FakeTaskScheduler(sc, ("exec1", "host1"),
("exec1.1", "host1"), ("exec2", "host2"))
// affinity to exec1 on host1 - which we will fail.
val taskSet = FakeTask.createTaskSet(1, Seq(TaskLocation("host1", "exec1")))
val clock = new FakeClock
val manager = new TaskSetManager(sched, taskSet, 4, clock)

{
val offerResult = manager.resourceOffer("exec1", "host1", 1, TaskLocality.PROCESS_LOCAL)
assert(offerResult.isDefined, "Expect resource offer to return a task")

assert(offerResult.get.index === 0)
assert(offerResult.get.executorId === "exec1")

// Cause exec1 to fail : failure 1
manager.handleFailedTask(offerResult.get.taskId, TaskState.FINISHED, TaskResultLost)
assert(!sched.taskSetsFailed.contains(taskSet.id))

// Ensure scheduling on exec1 fails after failure 1 due to blacklist
assert(manager.resourceOffer("exec1", "host1", 1, TaskLocality.PROCESS_LOCAL).isEmpty)
assert(manager.resourceOffer("exec1", "host1", 1, TaskLocality.NODE_LOCAL).isEmpty)
assert(manager.resourceOffer("exec1", "host1", 1, TaskLocality.RACK_LOCAL).isEmpty)
assert(manager.resourceOffer("exec1", "host1", 1, TaskLocality.ANY).isEmpty)
}

// Run the task on exec1.1 - should work, and then fail it on exec1.1
{
val offerResult = manager.resourceOffer("exec1.1", "host1", 1, TaskLocality.NODE_LOCAL)
assert(offerResult.isDefined,
"Expect resource offer to return a task for exec1.1, offerResult = " + offerResult)

assert(offerResult.get.index === 0)
assert(offerResult.get.executorId === "exec1.1")

// Cause exec1.1 to fail : failure 2
manager.handleFailedTask(offerResult.get.taskId, TaskState.FINISHED, TaskResultLost)
assert(!sched.taskSetsFailed.contains(taskSet.id))

// Ensure scheduling on exec1.1 fails after failure 2 due to blacklist
assert(manager.resourceOffer("exec1.1", "host1", 1, TaskLocality.NODE_LOCAL).isEmpty)
}

// Run the task on exec2 - should work, and then fail it on exec2
{
val offerResult = manager.resourceOffer("exec2", "host2", 1, TaskLocality.ANY)
assert(offerResult.isDefined, "Expect resource offer to return a task")

assert(offerResult.get.index === 0)
assert(offerResult.get.executorId === "exec2")

// Cause exec2 to fail : failure 3
manager.handleFailedTask(offerResult.get.taskId, TaskState.FINISHED, TaskResultLost)
assert(!sched.taskSetsFailed.contains(taskSet.id))

// Ensure scheduling on exec2 fails after failure 3 due to blacklist
assert(manager.resourceOffer("exec2", "host2", 1, TaskLocality.ANY).isEmpty)
}

// After reschedule delay, scheduling on exec1 should be possible.
clock.advance(rescheduleDelay)

{
val offerResult = manager.resourceOffer("exec1", "host1", 1, TaskLocality.PROCESS_LOCAL)
assert(offerResult.isDefined, "Expect resource offer to return a task")

assert(offerResult.get.index === 0)
assert(offerResult.get.executorId === "exec1")

assert(manager.resourceOffer("exec1", "host1", 1, TaskLocality.PROCESS_LOCAL).isEmpty)

// Cause exec1 to fail : failure 4
manager.handleFailedTask(offerResult.get.taskId, TaskState.FINISHED, TaskResultLost)
}

// we have failed the same task 4 times now : task id should now be in taskSetsFailed
assert(sched.taskSetsFailed.contains(taskSet.id))
}

def createTaskResult(id: Int): DirectTaskResult[Int] = {
val valueSer = SparkEnv.get.serializer.newInstance()
new DirectTaskResult[Int](valueSer.serialize(id), mutable.Map.empty, new TaskMetrics)
Expand Down

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