cloud-fan commented on a change in pull request #22806: [SPARK-25250][CORE] :
Late zombie task completions handled correctly even before new taskset launched
URL: https://github.com/apache/spark/pull/22806#discussion_r246998710
##########
File path:
core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala
##########
@@ -286,6 +286,44 @@ private[spark] class TaskSchedulerImpl(
}
}
+ /**
+ * SPARK-25250: Whenever any Task gets successfully completed, we simply
mark the
+ * corresponding partition id as completed in all attempts for that
particular stage and
+ * additionally, for a Result Stage, we also kill the remaining task
attempts running on the
+ * same partition. As a result, we do not see any Killed tasks due to
+ * TaskCommitDenied Exceptions showing up in the UI. When this method is
called from
+ * DAGScheduler.scala on a task completion event being fired, it is assumed
that the new
+ * TaskSet has already been created and registered. However, a small
possibility does exist
+ * that when this method gets called, possibly the new TaskSet might have
not been added
+ * to taskSetsByStageIdAndAttempt. In such a case, we might still hit the
same issue. However,
+ * the above scenario has not yet been reproduced.
+ */
+ override def completeTasks(partitionId: Int, stageId: Int, killTasks:
Boolean): Unit = {
+ taskSetsByStageIdAndAttempt.getOrElse(stageId, Map()).values.foreach { tsm
=>
+ tsm.partitionToIndex.get(partitionId) match {
+ case Some(index) =>
+ tsm.markPartitionAsAlreadyCompleted(index)
Review comment:
I don't see any downside of marking `successful(index) = true`.
- If `tsm` is active and the task is pending to run, I think killing the
task is a no-op, but maybe better to not send the KillTask request to avoid
overhead. `successful(index) = true` is needed here to finish the `tsm`.
- if `tsm` is active and the task is running. Killing the task will probably
save resource, and `successful(index) = true` is needed here to finish the
`tsm`.
- if `tsm` is zoombie, `successful(index) = true` is a no-op(but no
overhead) as a zombie `tsm` will never be marked as finished. Killing the task
may have benefit if the task is still running.
If we want to be 100% safe and eliminate any perf regression, maybe the
simplest choice is to not kill the task, but just `successful(index) = true`.
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