[
https://issues.apache.org/jira/browse/HIVE-23443?focusedWorklogId=433819&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-433819
]
ASF GitHub Bot logged work on HIVE-23443:
-----------------------------------------
Author: ASF GitHub Bot
Created on: 15/May/20 18:11
Start Date: 15/May/20 18:11
Worklog Time Spent: 10m
Work Description: pgaref commented on a change in pull request #1012:
URL: https://github.com/apache/hive/pull/1012#discussion_r425967771
##########
File path:
llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java
##########
@@ -884,10 +885,20 @@ private void finishableStateUpdated(TaskWrapper
taskWrapper, boolean newFinishab
taskWrapper.updateCanFinishForPriority(newFinishableState);
forceReinsertIntoQueue(taskWrapper, isRemoved);
} else {
- taskWrapper.updateCanFinishForPriority(newFinishableState);
- if (!newFinishableState && !taskWrapper.isInPreemptionQueue()) {
- // No need to check guaranteed here; if it was false we would
already be in the queue.
+ // if speculative task, any finishable state change should re-order
the queue as speculative tasks are always
+ // not-guaranteed (re-order helps put non-finishable's ahead of
finishable)
+ if (!taskWrapper.isGuaranteed()) {
+ removeFromPreemptionQueue(taskWrapper);
+ taskWrapper.updateCanFinishForPriority(newFinishableState);
addToPreemptionQueue(taskWrapper);
+ } else {
+ // if guaranteed task, if the finishable state changed to
non-finishable and if the task doesn't exist
+ // pre-emption queue, then add it so that it becomes candidate to
kill
+ taskWrapper.updateCanFinishForPriority(newFinishableState);
Review comment:
Can there be a case where we have a Guaranteed task that changes from
non-finishable to finishable and is only part of the preemptionQueue?
Under that scenario our code (and the old code) would remove it from
preemptionQ and it would not be part of any other Q.
From the code below it seems that this can indeed happen:
https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java#L776
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Issue Time Tracking
-------------------
Worklog Id: (was: 433819)
Remaining Estimate: 0h
Time Spent: 10m
> LLAP speculative task pre-emption seems to be not working
> ---------------------------------------------------------
>
> Key: HIVE-23443
> URL: https://issues.apache.org/jira/browse/HIVE-23443
> Project: Hive
> Issue Type: Bug
> Reporter: Prasanth Jayachandran
> Assignee: Prasanth Jayachandran
> Priority: Major
> Attachments: HIVE-23443.1.patch, HIVE-23443.2.patch
>
> Time Spent: 10m
> Remaining Estimate: 0h
>
> I think after HIVE-23210 we are getting a stable sort order and it is causing
> pre-emption to not work in certain cases.
> {code:java}
> "attempt_1589167813851_0000_119_01_000008_0
> (hive_20200511055921_89598f09-19f1-4969-ab7a-82e2dd796273-119/Map 1, started
> at 2020-05-11 05:59:22, in preemption queue, can finish)",
> "attempt_1589167813851_0008_84_01_000008_1
> (hive_20200511055928_7ae29ca3-e67d-4d1f-b193-05651023b503-84/Map 1, started
> at 2020-05-11 06:00:23, in preemption queue, can finish)" {code}
> Scheduler only peek's at the pre-emption queue and looks at whether it is
> non-finishable.
> [https://github.com/apache/hive/blob/master/llap-server/src/java/org/apache/hadoop/hive/llap/daemon/impl/TaskExecutorService.java#L420]
> In the above case, all tasks are speculative but state change is not
> triggering pre-emption queue re-ordering so peek() always returns canFinish
> task even though non-finishable tasks are in the queue.
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