[jira] [Created] (YARN-1921) Allow to override queue prefix, where new queues created

["Andrey Stepachev (JIRA)" <ji...@apache.org>]

Andrey Stepachev created YARN-1921:
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             Summary: Allow to override queue prefix, where new queues created
                 Key: YARN-1921
                 URL: https://issues.apache.org/jira/browse/YARN-1921
             Project: Hadoop YARN
          Issue Type: Improvement
          Components: scheduler
    Affects Versions: 2.3.0
         Environment: Yarn 2.3.0
            Reporter: Andrey Stepachev


Fair scheduler has a couple of QueuePlacementRules. Those rules can create queues, if they not exists with hardcoded prefix "root.". 

Consider an example: we have a placement rule, which creates user's queue if it not exists. Current implementation creates it at "root." prefix  Suppose that this user runs a big job. In that case it will get a fair share of resources because queue will be created at 'root.' with default settings, and that affects all other users of the cluster. 
Of course, FairScheduler can place such users to default queue, but in that case if user submits a big queue it will eats resources of whole queue, and we know that no preemption can be done within one queue (Or i'm wrong?). So effectively one user can usurp all default queue resources.

To solve that I created a patch, which allows to override "root." prefix in QueuePlacementRules. Thats gives us flexibility to automatically create queues for users or group of users under predefined queue. So, every user will get a separate queue and will share parent queue resources and can't usurp all resources, because parent node can be configured to preempt tasks.

Consider example (parent queue specified for each rule):
{code:title=policy.xml|borderStyle=solid}
<queuePlacementPolicy>
  <rule name='specified' parent='granted'/>
  <rule name='user'  parent='guests'/>
</queuePlacementPolicy>
{code}

With such definition queue requirements will give us:
{code:title=Example.java|borderStyle=solid}
"root.granted.specifiedq" == policy.assignAppToQueue("specifiedq", "someuser");
"root.guests.someuser" == policy.assignAppToQueue("default", "someuser");
"root.guests.otheruser" == policy.assignAppToQueue("default", "otheruser"); 
{code}



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