adithyachakilam opened a new pull request, #17356:
URL: https://github.com/apache/druid/pull/17356
### Description
There are two things that are done after a scaling action is successfully
initiated,
- Clear the collected lag metrics until now
- Record the time so that we don't scale for next
`minTriggerScaleActionFrequencyMillis`
Currently, these two actions are decoupled and there could be cases when
supervisor could be publishing or when `minTriggerScaleActionFrequencyMillis`
has not yet been elapsed in which the scaling action could be skipped. While
skipping that action, we are clearing the collected lag metrics but not
actually updating the task count. SO the next decision for scaling would be
based on looking at shorter windows than configured which could cause more
scaling actions than required.
This PR updates to clear the collected lag only when supervisor is truly
scaled.
<hr>
##### Key changed/added classes in this PR
* `SeekableStreamSupervisor`
* `LagBasedAutoScaler`
<hr>
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- [ ] added integration tests.
- [ ] been tested in a test Druid cluster.
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