Github user kayousterhout commented on a diff in the pull request:
https://github.com/apache/spark/pull/14079#discussion_r72536190
--- Diff:
core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala ---
@@ -310,12 +343,41 @@ private[spark] class TaskSchedulerImpl(
}
}
- // Randomly shuffle offers to avoid always placing tasks on the same
set of workers.
- val shuffledOffers = Random.shuffle(offers)
+ // ensure that we periodically check if executors can be removed from
the blacklist, without
+ // requiring a separate thread and added synchronization overhead
+ blacklistTracker.foreach(_.expireExecutorsInBlacklist())
+
+ val sortedTaskSets = rootPool.getSortedTaskSetQueue
+ val filteredOffers: IndexedSeq[WorkerOffer] = (blacklistTracker match {
+ case Some(bl) => offers.filter { offer =>
+ !bl.isNodeBlacklisted(offer.host) &&
+ !bl.isExecutorBlacklisted(offer.executorId)
+ }
+ case None => offers
+ }) match {
+ // toIndexedSeq always makes an *immutable* IndexedSeq, though we
don't care if its mutable
+ // or immutable. So we do this to avoid making a pointless copy
+ case is: IndexedSeq[WorkerOffer] => is
+ case other: Seq[WorkerOffer] => other.toIndexedSeq
+ }
+ if (offers.nonEmpty && filteredOffers.isEmpty) {
+ // Its possible that all the executors are now blacklisted, though
we haven't aborted stages
+ // during the check in resourceOfferSingleTaskSet. If so, fail all
existing task sets to
+ // avoid unschedulability.
+ if (areAllExecutorsBlacklisted()) {
--- End diff --
This is an optimization right? (it's not needed for correctness?) If so,
can we remove it? Worried about the complexity of all of this -- and this seems
rare enough that the delta in time to failure isn't super important.
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