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https://issues.apache.org/jira/browse/YARN-5540?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jason Lowe updated YARN-5540:
-----------------------------
Attachment: YARN-5540.002.patch
Updating the patch to use a ConcurrentSkipListMap instead of a TreeMap. This
is not going to be as cheap as having the iterator do the removal, but it's far
less code change and more robust if we allow other threads to update the
requests as the scheduler is examining them.
I also updated the TODO comment and added a check for the CME possibility which
catches the error from the previous patch.
> scheduler spends too much time looking at empty priorities
> ----------------------------------------------------------
>
> Key: YARN-5540
> URL: https://issues.apache.org/jira/browse/YARN-5540
> Project: Hadoop YARN
> Issue Type: Improvement
> Components: capacity scheduler, fairscheduler, resourcemanager
> Affects Versions: 2.7.2
> Reporter: Nathan Roberts
> Assignee: Jason Lowe
> Attachments: YARN-5540.001.patch, YARN-5540.002.patch
>
>
> We're starting to see the capacity scheduler run out of scheduling horsepower
> when running 500-1000 applications on clusters with 4K nodes or so.
> This seems to be amplified by TEZ applications. TEZ applications have many
> more priorities (sometimes in the hundreds) than typical MR applications and
> therefore the loop in the scheduler which examines every priority within
> every running application, starts to be a hotspot. The priorities appear to
> stay around forever, even when there is no remaining resource request at that
> priority causing us to spend a lot of time looking at nothing.
> jstack snippet:
> {noformat}
> "ResourceManager Event Processor" #28 prio=5 os_prio=0 tid=0x00007fc2d453e800
> nid=0x22f3 runnable [0x00007fc2a8be2000]
> java.lang.Thread.State: RUNNABLE
> at
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.SchedulerApplicationAttempt.getResourceRequest(SchedulerApplicationAttempt.java:210)
> - eliminated <0x00000005e73e5dc0> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp)
> at
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.LeafQueue.assignContainers(LeafQueue.java:852)
> - locked <0x00000005e73e5dc0> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.common.fica.FiCaSchedulerApp)
> - locked <0x00000003006fcf60> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.LeafQueue)
> at
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainersToChildQueues(ParentQueue.java:527)
> - locked <0x00000003001b22f8> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue)
> at
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue.assignContainers(ParentQueue.java:415)
> - locked <0x00000003001b22f8> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.ParentQueue)
> at
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler.allocateContainersToNode(CapacityScheduler.java:1224)
> - locked <0x0000000300041e40> (a
> org.apache.hadoop.yarn.server.resourcemanager.scheduler.capacity.CapacityScheduler)
> {noformat}
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