Github user roxchkplusony commented on a diff in the pull request: https://github.com/apache/spark/pull/3483#discussion_r21008476 --- Diff: core/src/main/scala/org/apache/spark/scheduler/cluster/CoarseGrainedSchedulerBackend.scala --- @@ -127,7 +127,13 @@ class CoarseGrainedSchedulerBackend(scheduler: TaskSchedulerImpl, val actorSyste makeOffers() case KillTask(taskId, executorId, interruptThread) => - executorDataMap(executorId).executorActor ! KillTask(taskId, executorId, interruptThread) + executorDataMap.get(executorId) match { + case Some(executorInfo) => + executorInfo.executorActor ! KillTask(taskId, executorId, interruptThread) + case None => + // Ignoring the task kill since the executor is not registered. + logWarning(s"Attempted to kill task $taskId for unknown executor $executorId.") + } --- End diff -- I understand the general objection (pattern matching is usually a cop-out to better functional style) but that's not the appropriate pattern here. map is specifically designed to apply a morphism from A -> B (in Scala, f: A => B) to describe Option[A] -> Option[B]. What we are doing here is applying a choice of side effect, not a value, depending on the concrete Option. The example is (Option[A] -> Option[Unit]) -> Unit with misuse of monadic operators. Also, this code applies patterns found consistently elsewhere in this class file. If you believe strongly in this pattern, would you mind opening a PR for review?
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