Github user markhamstra commented on a diff in the pull request:

    https://github.com/apache/spark/pull/15335#discussion_r82944965
  
    --- Diff: core/src/main/scala/org/apache/spark/scheduler/DAGScheduler.scala 
---
    @@ -1255,27 +1255,46 @@ class DAGScheduler(
                   s"longer running")
               }
     
    -          if (disallowStageRetryForTest) {
    -            abortStage(failedStage, "Fetch failure will not retry stage 
due to testing config",
    -              None)
    -          } else if 
(failedStage.failedOnFetchAndShouldAbort(task.stageAttemptId)) {
    -            abortStage(failedStage, s"$failedStage (${failedStage.name}) " 
+
    -              s"has failed the maximum allowable number of " +
    -              s"times: ${Stage.MAX_CONSECUTIVE_FETCH_FAILURES}. " +
    -              s"Most recent failure reason: ${failureMessage}", None)
    -          } else {
    -            if (failedStages.isEmpty) {
    -              // Don't schedule an event to resubmit failed stages if 
failed isn't empty, because
    -              // in that case the event will already have been scheduled.
    -              // TODO: Cancel running tasks in the stage
    -              logInfo(s"Resubmitting $mapStage (${mapStage.name}) and " +
    -                s"$failedStage (${failedStage.name}) due to fetch failure")
    -              messageScheduler.schedule(new Runnable {
    -                override def run(): Unit = 
eventProcessLoop.post(ResubmitFailedStages)
    -              }, DAGScheduler.RESUBMIT_TIMEOUT, TimeUnit.MILLISECONDS)
    +          val shouldAbortStage =
    +            failedStage.failedOnFetchAndShouldAbort(task.stageAttemptId) ||
    +            disallowStageRetryForTest
    +
    +          if (shouldAbortStage) {
    +            val abortMessage = if (disallowStageRetryForTest) {
    +              "Fetch failure will not retry stage due to testing config"
    +            } else {
    +              s"""$failedStage (${failedStage.name})
    +                 |has failed the maximum allowable number of
    +                 |times: ${Stage.MAX_CONSECUTIVE_FETCH_FAILURES}.
    +                 |Most recent failure reason: 
$failureMessage""".stripMargin.replaceAll("\n", " ")
                 }
    +            abortStage(failedStage, abortMessage, None)
    +          } else { // update failedStages and make sure a 
ResubmitFailedStages event is enqueued
    +            // TODO: Cancel running tasks in the failed stage -- cf. 
SPARK-17064
    +            val noResubmitEnqueued = !failedStages.contains(failedStage)
                 failedStages += failedStage
                 failedStages += mapStage
    +            if (noResubmitEnqueued) {
    +              // We expect one executor failure to trigger many 
FetchFailures in rapid succession,
    +              // but all of those task failures can typically be handled 
by a single resubmission of
    +              // the failed stage.  We avoid flooding the scheduler's 
event queue with resubmit
    +              // messages by checking whether a resubmit is already in the 
event queue for the
    +              // failed stage.  If there is already a resubmit enqueued 
for a different failed
    +              // stage, that event would also be sufficient to handle the 
current failed stage, but
    +              // producing a resubmit for each failed stage makes 
debugging and logging a little
    +              // simpler while not producing an overwhelming number of 
scheduler events.
    +              logInfo(
    +                s"Resubmitting $mapStage (${mapStage.name}) and " +
    +                s"$failedStage (${failedStage.name}) due to fetch failure"
    +              )
    +              messageScheduler.schedule(
    --- End diff --
    
    Ah, sorry for ascribing the prior comment to your preferences.  That 
comment actually did make sense a long time ago when the resubmitting of stages 
really was done periodically by an Akka scheduled event that fired every 
something seconds.  I'm pretty sure the RESUBMIT_TIMEOUT stuff is also legacy 
code that doesn't make sense and isn't necessary any more.
    
    So, do you want to do the follow-up PR to get rid of it, or shall I? 


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