Github user squito commented on a diff in the pull request:
https://github.com/apache/spark/pull/13603#discussion_r67067563
--- Diff:
core/src/main/scala/org/apache/spark/scheduler/TaskSchedulerImpl.scala ---
@@ -280,10 +280,54 @@ private[spark] class TaskSchedulerImpl(
}
}
}
+ if (!launchedTask && isTaskSetCompletelyBlacklisted(taskSet)) {
+ taskSet.abort(s"Aborting ${taskSet.taskSet} because it has a task
which cannot be scheduled" +
+ s" on any executor due to blacklists.")
+ }
return launchedTask
}
/**
+ * Check whether the given task set has been blacklisted to the point
that it can't run anywhere.
+ *
+ * It is possible that this taskset has become impossible to schedule
*anywhere* due to the
+ * blacklist. The most common scenario would be if there are fewer
executors than
+ * spark.task.maxFailures. We need to detect this so we can fail the
task set, otherwise the job
+ * will hang.
+ *
+ * The check here is a balance between being sure to catch the issue,
but not wasting
+ * too much time inside the scheduling loop. Just check if the last
task is schedulable
+ * on any of the available executors. So this is O(numExecutors)
worst-case, but it'll
+ * really be fast unless you've got a bunch of things blacklisted. Its
possible it won't detect
+ * the unschedulable task immediately, but if it returns false, there is
at least *some* task
+ * that is schedulable, and after scheduling all of those, we'll
eventually find the unschedulable
+ * task.
+ */
+ private[scheduler] def isTaskSetCompletelyBlacklisted(
--- End diff --
yeah I put it here b/c in the blacklisting stuff I'm still working on, I
felt it made more sense outside TaskSetManager, since blacklisting extends
beyond a single taskset (executor & node blacklisting). But I'll change it
here, and we can revisit that discussion when looking at that change.
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