capistrant opened a new pull request #10287:
URL: https://github.com/apache/druid/pull/10287


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   ### Description
   
   <!-- Describe the goal of this PR, what problem are you fixing. If there is 
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   Allows cluster admin to disable the LogUsedSegments coordinator duty if they 
so choose. This duty does not have any impact on successive duties so disabling 
it does not cause any change to the state of the cluster after coordination 
duties complete.
   
   As an admin for a large enterprise cluster myself, I have been on the hunt 
for any optimization I can find in the lifecycle of the coordinator. This patch 
appears to be low hanging fruit in my efforts. This duty takes ~10 seconds to 
complete on our largest cluster. We have never used debug logging to log our 
segments and we have never checked the emitters alert stream for alerts on 
segments with size `<0`. Therefore, I think it makes sense to give admins the 
ability to toggle this duty on and off as they see fit.
   
   <!-- Describe your patch: what did you change in code? How did you fix the 
problem? -->
   I added a config to the `DruidCoordinatorConfig`. The naming scheme of this 
config can be easily change as the community sees fit. I made my choice in the 
hope that it is self-explanatory and allows for more future duty specific 
configs to be added following the same scheme.
   
   This config defaults to having the LogUsedSegments duty enabled (keeping 
inline with current functionality). When the coordinator is becoming a leader 
and creating its duties, it consults the config object to find out if the 
LogUsedSegments duty should be added to the duty lists for historical segment 
management and indexing.
   
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   <hr>
   
   This PR has:
   - [X] been self-reviewed.
   - [X] added documentation for new or modified features or behaviors.
   - [X] added unit tests or modified existing tests to cover new code paths, 
ensuring the threshold for [code 
coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md)
 is met.
   - [X] been tested in a test Druid cluster.
   
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   <hr>
   
   ##### Key changed/added classes in this PR
    * `DruidCoordinatorConfig`
   * `DruidCoordinator`
   


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