Github user kayousterhout commented on a diff in the pull request: https://github.com/apache/spark/pull/15644#discussion_r88526915 --- 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 --- End diff -- Why do you need to consider the number of cores? My understanding is that resourceOfferSingleTaskSet will only be called repeatedly (i.e., once for each core) when tasks are successfully launched, but because this test is checking for blacklisted executors / nodes, resourceOfferSingleTaskSet won't launch a task on the blacklisted nodes.
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