Tao Jie commented on YARN-4462:

Hi, [~sunilg]
Thank you for reply!
I agree that "do-not-preempt" application breaks fairness of resource 
In reality, cost of preempting a long-run service(especially service needs 
all-or-nothing resource) may be much more than preempting a MR job. When a MR 
job and a long-run service running in one queue and need to be preempted, I 
prefer to preempt the MR job before the long-run service even if the MR job is 
submitted earlier.
We do have related configuration to adjust logic of preemption(maybe higher app 
priority). We can also have explicit flag to tell the scheduler that just do 
not preempt this queue or app, isn't it?

> Scheduler should prevent certain application from being preempted
> -----------------------------------------------------------------
>                 Key: YARN-4462
>                 URL: https://issues.apache.org/jira/browse/YARN-4462
>             Project: Hadoop YARN
>          Issue Type: Improvement
>          Components: scheduler
>    Affects Versions: 2.6.0
>            Reporter: Tao Jie
> When scheduler preemption is enabled, applications could be preempted if they 
> obtain resource over they should take. 
> When a mapreduce application is preempted some resource, it just runs slower. 
> However, when the preempted application is a long-run service, such as tomcat 
> running in slider, the service would fail.
> So we should have a flag for application to indicate the scheduler that those 
> application should not be preempted. 

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