Github user kayousterhout commented on a diff in the pull request:
https://github.com/apache/spark/pull/15644#discussion_r88526435
--- 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
--- End diff --
This test is pretty complicated, and hard to reason about as a result. Can
you simplify fit by making a resource offer for just one executor/node, which
is the executor/node that's blacklisted? Then the list of executors / nodes to
check is small (just 1), and you know exactly the number of times
isNodeBlacklistedForTaskSet should be called (# locality levels) because there
aren't any ordering issues?
I'm proposing this because it took me a while to read/understand this test,
which makes me concerned about maintainability.
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
