Github user squito commented on a diff in the pull request:
https://github.com/apache/spark/pull/15644#discussion_r88609776
--- Diff:
core/src/test/scala/org/apache/spark/scheduler/TaskSchedulerImplSuite.scala ---
@@ -282,6 +317,188 @@ class TaskSchedulerImplSuite extends SparkFunSuite
with LocalSparkContext with B
assert(!failedTaskSet)
}
+ test("scheduled tasks obey task and stage blacklists") {
+ taskScheduler = setupSchedulerWithMockTaskSetBlacklist()
+ (0 to 2).foreach {stageId =>
+ val taskSet = FakeTask.createTaskSet(numTasks = 2, stageId =
stageId, stageAttemptId = 0)
+ taskScheduler.submitTasks(taskSet)
+ }
+
+ // Setup our mock blacklist:
+ // * stage 0 is blacklisted on node "host1"
+ // * stage 1 is blacklisted on executor "executor3"
+ // * stage 0, partition 0 is blacklisted on executor 0
+ // (mocked methods default to returning false, ie. no blacklisting)
+
when(stageToMockTaskSetBlacklist(0).isNodeBlacklistedForTaskSet("host1")).thenReturn(true)
+
when(stageToMockTaskSetBlacklist(1).isExecutorBlacklistedForTaskSet("executor3"))
+ .thenReturn(true)
+
when(stageToMockTaskSetBlacklist(0).isExecutorBlacklistedForTask("executor0",
0))
+ .thenReturn(true)
+
+ val offers = IndexedSeq(
+ new WorkerOffer("executor0", "host0", 1),
+ new WorkerOffer("executor1", "host1", 1),
+ new WorkerOffer("executor2", "host1", 1),
+ new WorkerOffer("executor3", "host2", 10)
+ )
+ val firstTaskAttempts = taskScheduler.resourceOffers(offers).flatten
+ // We should schedule all tasks.
+ assert(firstTaskAttempts.size === 6)
+ // Whenever we schedule a task, we must consult the node and executor
blacklist. (The test
+ // doesn't check exactly what checks are made because the offers get
shuffled.)
+ (0 to 2).foreach { stageId =>
+ verify(stageToMockTaskSetBlacklist(stageId), atLeast(1))
+ .isNodeBlacklistedForTaskSet(anyString())
+ verify(stageToMockTaskSetBlacklist(stageId), atLeast(1))
+ .isExecutorBlacklistedForTaskSet(anyString())
+ }
+
+ def tasksForStage(stageId: Int): Seq[TaskDescription] = {
+ firstTaskAttempts.filter{_.name.contains(s"stage $stageId")}
+ }
+ tasksForStage(0).foreach { task =>
+ // executors 1 & 2 blacklisted for node
+ // executor 0 blacklisted just for partition 0
+ if (task.index == 0) {
+ assert(task.executorId === "executor3")
+ } else {
+ assert(Set("executor0", "executor3").contains(task.executorId))
+ }
+ }
+ tasksForStage(1).foreach { task =>
+ // executor 3 blacklisted
+ assert("executor3" != task.executorId)
+ }
+ // no restrictions on stage 2
+
+ // Finally, just make sure that we can still complete tasks as usual
with blacklisting
+ // in effect. Finish each of the tasksets -- taskset 0 & 1 complete
successfully, taskset 2
+ // fails.
+ (0 to 2).foreach { stageId =>
+ val tasks = tasksForStage(stageId)
+ val tsm = taskScheduler.taskSetManagerForAttempt(stageId, 0).get
+ val valueSer = SparkEnv.get.serializer.newInstance()
+ if (stageId == 2) {
+ // Just need to make one task fail 4 times.
+ var task = tasks(0)
+ val taskIndex = task.index
+ (0 until 4).foreach { attempt =>
+ assert(task.attemptNumber === attempt)
+ tsm.handleFailedTask(task.taskId, TaskState.FAILED,
TaskResultLost)
+ val nextAttempts =
+
taskScheduler.resourceOffers(IndexedSeq(WorkerOffer("executor4", "host4",
1))).flatten
+ if (attempt < 3) {
+ assert(nextAttempts.size === 1)
+ task = nextAttempts(0)
+ assert(task.index === taskIndex)
+ } else {
+ assert(nextAttempts.size === 0)
+ }
+ }
+ // End the other task of the taskset, doesn't matter whether it
succeeds or fails.
+ val otherTask = tasks(1)
+ val result = new
DirectTaskResult[Int](valueSer.serialize(otherTask.taskId), Seq())
+ tsm.handleSuccessfulTask(otherTask.taskId, result)
+ } else {
+ tasks.foreach { task =>
+ val result = new
DirectTaskResult[Int](valueSer.serialize(task.taskId), Seq())
+ tsm.handleSuccessfulTask(task.taskId, result)
+ }
+ }
+ assert(tsm.isZombie)
+ }
+ }
+
+ /**
+ * Helper for performance tests. Takes the explicitly blacklisted nodes
and executors; verifies
+ * that the blacklists are used efficiently to ensure scheduling is not
O(numPendingTasks).
+ */
+ private def blacklistPerformanceCheck(
+ nodeBlacklist: Seq[String],
+ execBlacklist: Seq[String]): Unit = {
+ // When an executor or node is blacklisted, we want to make sure that
we don't try scheduling
+ // each pending task, one by one, to discover they are all
blacklisted. This is important for
+ // performance -- if we did check each task one-by-one, then
responding to a resource offer
+ // (which is usually O(1)-ish) would become O(numPendingTasks), which
would slow down
+ // scheduler throughput and slow down scheduling even on healthy
executors.
+ // Here, we check a proxy for the runtime -- we make sure the
scheduling is short-circuited
+ // at the node or executor blacklist, so we never check the per-task
blacklist. We also make
+ // sure we don't check the node & executor blacklist for the entire
taskset O(numPendingTasks)
+ // times.
+
+ taskScheduler = setupSchedulerWithMockTaskSetBlacklist()
+ // we schedule 500 tasks so we can clearly distinguish anything that
is O(numPendingTasks)
+ val taskSet = FakeTask.createTaskSet(numTasks = 500, stageId = 0,
stageAttemptId = 0)
+ taskScheduler.submitTasks(taskSet)
+
+ val offers = IndexedSeq(
+ new WorkerOffer("executor1", "host1", 1),
+ new WorkerOffer("executor2", "host1", 1),
+ new WorkerOffer("executor3", "host2", 1)
+ )
+ // We should check the node & exec blacklists, but only O(numOffers),
not O(numPendingTasks)
+ // times. Its O(numOffers), not exactly numOffers, because we offer
resources multiple
+ // times. An upper bound on the worst case is -- we check it once for
every core at each
+ // locality level. (We could tighten the bound a bit but that should
be a good enough check.)
+ val numCoresOnAllOffers = offers.map(_.cores).sum
+ val numLocalityLevels = TaskLocality.values.size
+ val maxBlacklistChecks = numCoresOnAllOffers * numLocalityLevels
+
+ // Setup the blacklist, and get back a list of the executors & nodes
that have any blacklisting
+ // (even implicit blacklisting).
+
+ nodeBlacklist.foreach { node =>
+
when(stageToMockTaskSetBlacklist(0).isNodeBlacklistedForTaskSet(node)).thenReturn(true)
+ }
+ execBlacklist.foreach { exec =>
+
when(stageToMockTaskSetBlacklist(0).isExecutorBlacklistedForTaskSet(exec)).thenReturn(true)
+ }
+ val nodesForBlacklistedExecutors = offers.filter { offer =>
+ execBlacklist.contains(offer.executorId)
+ }.map(_.host).toSet.toSeq
+ val nodesToCheck = nodeBlacklist ++ nodesForBlacklistedExecutors
+ val execsForBlacklistedNodes = offers.filter { offer =>
+ nodeBlacklist.contains(offer.host)
+ }.map(_.executorId).toSeq
+ val executorsToCheck = execBlacklist ++ execsForBlacklistedNodes
+
+ // Schedule a taskset, do a bit of basic sanity checking (that our
test is operating the way its
+ // supposed to).
--- End diff --
executorsToCheck is all executors that are effectively blacklisted,
explicitly or implicitly via the node blacklist. I'll update the name and add
a comment.
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