Bugfixes/improvements to scheduler

core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala

@@ -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
  }
  }

core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala

@@ -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)
@@ -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
 
@@ -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
@@ -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
@@ -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)) {
@@ -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
@@ -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
@@ -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))
  }
@@ -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))
  }
  }
@@ -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()
  }
 
@@ -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 =>
@@ -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)) {
@@ -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(

core/src/test/scala/org/apache/spark/scheduler/TaskSetManagerSuite.scala

@@ -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)