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https://issues.apache.org/jira/browse/YARN-8191?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16465436#comment-16465436
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Wilfred Spiegelenburg commented on YARN-8191:
---------------------------------------------
thank you for the updated patch:
* In {{removeEmptyDynamicQueues}} why are we not using {{getLeafQueues}}
instead of {{getQueues}}? The queue cleanup should start with the leafs and it
removes the need to check if the queue has children.
* In {{removeEmptyDynamicQueues}} instead of adding to parentQueuesToCheck
without checks should we not only add a parent queue if that queue is dynamic?
That also removes the need for the root queue check while iterating and the
only check for child queues is needed.
* In {{updateAllocationConfiguration}} there should be no need to go over all
the queues and set the isDynamic flag. The flag should be set on creation and
never updated after that unless it was an incompatible queue. We should add a
new getLeafQueue and getParentQueue method which takes the isDynamic flag and
sets it. It then can call the existing method. The only place that we would
call the new method would be in {{updateAllocationConfiguration}}. The old
version of the method would stay as is as the isDynamic flag set to {{true}} by
default. That should handle all placement rules etc.
* To clean up any removed configured, non dynamic, queues we need to be smart
and we do not want to walk over all queues. In {{onReload}} we have the old and
new configured queues and we can easily build a list of queues which need to
become dynamic:
{code}
Set<String> toDynamic = new HashSet<>();
if (queueInfo != null) {
toDynamic.addAll(allocConf.getConfiguredQueues().get(FSQueueType.LEAF));
toDynamic.addAll(allocConf.getConfiguredQueues().get(FSQueueType.PARENT));
toDynamic.removeAll(queueInfo.configuredQueues.get(FSQueueType.LEAF));
toDynamic.removeAll(queueInfo.configuredQueues.get(FSQueueType.PARENT));
}
if (!toDynamic.isEmpty()) {
queueMgr.changeToDynamic(toDynamic);
}
{code}
The {{changeToDynamic}} just needs to walk over the set and set the flag. The
standard cleanup code for the dynamic queues will then take care of the cleanup
without needing lots of iterations. Building this diff of queues can happen
outside of locking in the FS.
* The logic behind {{getDynamicQueueNames}} is not correct: the
configuredQueues set as stored in the AllocationConfiguration only has queues
that are defined in the configuration. There can never be a dynamic queue in
that list. Dynamic queues can only be created via the placement rules. (see
previous comments)
* As a side node: {{getLeafQueues}} in the QueueManager should return an
ImmutableList of the leaf queues like we do in {{getQueues}}
> Fair scheduler: queue deletion without RM restart
> -------------------------------------------------
>
> Key: YARN-8191
> URL: https://issues.apache.org/jira/browse/YARN-8191
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: fairscheduler
> Affects Versions: 3.0.1
> Reporter: Gergo Repas
> Assignee: Gergo Repas
> Priority: Major
> Attachments: Queue Deletion in Fair Scheduler.pdf,
> YARN-8191.000.patch, YARN-8191.001.patch, YARN-8191.002.patch,
> YARN-8191.003.patch, YARN-8191.004.patch, YARN-8191.005.patch
>
>
> The Fair Scheduler never cleans up queues even if they are deleted in the
> allocation file, or were dynamically created and are never going to be used
> again. Queues always remain in memory which leads to two following issues.
> # Steady fairshares aren’t calculated correctly due to remaining queues
> # WebUI shows deleted queues, which is confusing for users (YARN-4022).
> We want to support proper queue deletion without restarting the Resource
> Manager:
> # Static queues without any entries that are removed from fair-scheduler.xml
> should be deleted from memory.
> # Dynamic queues without any entries should be deleted.
> # RM Web UI should only show the queues defined in the scheduler at that
> point in time.
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