Github user lirui-intel commented on a diff in the pull request:
https://github.com/apache/spark/pull/892#discussion_r13599131
--- Diff:
core/src/main/scala/org/apache/spark/scheduler/TaskSetManager.scala ---
@@ -388,7 +386,7 @@ private[spark] class TaskSetManager(
val curTime = clock.getTime()
var allowedLocality = getAllowedLocalityLevel(curTime)
- if (allowedLocality > maxLocality) {
+ if (allowedLocality > maxLocality &&
myLocalityLevels.contains(maxLocality)) {
allowedLocality = maxLocality // We're not allowed to search for
farther-away tasks
}
--- End diff --
@mridulm - Thanks for replying. In my opinion, however, relaxing the
allowed locality won't change the scheduling order. NODE_LOCAL tasks (if any)
still get scheduled before RACK_LOCAL ones. And if we allow RACK_LOCAL but get
a NODE_LOCAL task, currentLocalityIndex will be updated so that next time we
will use NODE_LOCAL as the constraint.
However, if we restrict up to PROCESS_LOCAL while it's in fact not valid
for the TaskSetManager, the NODE_LOCAL and RACK_LOCAL tasks will be skipped and
we may end up picking tasks from pendingTasksWithNoPrefs.
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