Sangjin Lee commented on YARN-4183:

Thanks [~vinodkv] for the suggestion. The following is my proposal.

- yarn.timeline-service.enabled should be interpreted as the config that 
indicates the timeline service daemon is up *both* on the client side and the 
server side
- specifically for the RM's system metrics publisher, it should continue to 
check both yarn.timeline-service.enabled and 
yarn.resourcemanager.system-metrics-publisher.enabled (which is the current 
code); if not, and the timeline service is not up (which is a totally valid 
situation), the system metrics publisher will have a continuous stream of write 
- there needs to be a strong client-side config for each framework (MR or tez) 
that controls whether it wants to use the timeline service; the client can use 
the timeline service only if *both* yarn.timeline-service.enabled is true and 
its own config is true

I hope the last point should address the original issue of this JIRA (if MR 
does not want to use the timeline service, it should be able to do so).

The decision to use the timeline service and get the delegation token should 
not hinge on which version is enabled IMO, as the version is another global 

Let me know if that sounds reasonable.

> Enabling generic application history forces every job to get a timeline 
> service delegation token
> ------------------------------------------------------------------------------------------------
>                 Key: YARN-4183
>                 URL: https://issues.apache.org/jira/browse/YARN-4183
>             Project: Hadoop YARN
>          Issue Type: Bug
>    Affects Versions: 2.7.1
>            Reporter: Mit Desai
>            Assignee: Mit Desai
>         Attachments: YARN-4183.1.patch
> When enabling just the Generic History Server and not the timeline server, 
> the system metrics publisher will not publish the events to the timeline 
> store as it checks if the timeline server and system metrics publisher are 
> enabled before creating a timeline client.
> To make it work, if the timeline service flag is turned on, it will force 
> every yarn application to get a delegation token.
> Instead of checking if timeline service is enabled, we should be checking if 
> application history server is enabled.

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