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Eric Payne commented on YARN-3275:
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This situation can happen under the following conditions:
- All of the resources in the cluster are being used
- {{QueueA}} is preemptable and over its absolute capacity (AKA guaranteed capacity)
- {{QueueB}} is not preemptable, over its absolute capacity, also over its absolute max capacity
(which can happen), and asking for more resources
In the above scenario, {{ProportionalCapacityPreemptionPolicy}} will subtract {{QueuB}}'s
ideal assigned value from its absolute max capacity value and get a negative number, which
will adjust it's ideally assigned resources downwards by that amount, which will result in
that amount getting preempted.
Regardless of the reason, if a queue is marked as unpreemptable, resources should never be
preempted from that queue.
> Preemption happening on non-preemptable queues
> ----------------------------------------------
>
> Key: YARN-3275
> URL: https://issues.apache.org/jira/browse/YARN-3275
> Project: Hadoop YARN
> Issue Type: Bug
> Affects Versions: 2.7.0
> Reporter: Eric Payne
> Assignee: Eric Payne
>
> YARN-2056 introduced the ability to turn preemption on and off at the queue level. In
cases where a queue goes over its absolute max capacity (YARN:3243, for example), containers
can be preempted from that queue, even though the queue is marked as non-preemptable.
> We are using this feature in large, busy clusters and seeing this behavior.
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