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[GitHub] [druid] AmatyaAvadhanula opened a new pull request, #13076: Independent Supervisor Creation/Updation/Termination
AmatyaAvadhanula opened a new pull request, #13076:
URL: https://github.com/apache/druid/pull/13076
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Fixes waiting of supervisor operations on those of others'
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### Description
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When a supervisor is being created, updated or terminated, it holds a lock in SupervisorManager, delaying these operations for other supervisors.
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By adding state specific locks and supervisor specific locks, different supervisors' operations can be made more decoupled.
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<hr>
##### Key changed/added classes in this PR
* `SupervisorManager`
<hr>
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Re: [PR] Independent Supervisor Creation/Updation/Termination (druid)
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #13076:
URL: https://github.com/apache/druid/pull/13076#issuecomment-1931000718
This pull request/issue has been closed due to lack of activity. If you think that
is incorrect, or the pull request requires review, you can revive the PR at any time.
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[GitHub] [druid] kfaraz commented on pull request #13076: Independent Supervisor Creation/Updation/Termination
Posted by GitBox <gi...@apache.org>.
kfaraz commented on PR #13076:
URL: https://github.com/apache/druid/pull/13076#issuecomment-1243746717
@AmatyaAvadhanula , thanks for taking a stab at this. Could you share some more details regarding why these changes are needed? I see that this would increase the possible concurrency of supervisor update operations, but some more details would be helpful.
If the intention is higher concurrency, I feel that the approach can be improved. Maps such as `autoscalers` etc are already `ConcurrentHashMap`s and don't really need separate locks. You could just perform atomic updates on them using methods like `computeIfAbsent()`.
But the real concern is the purpose of the original global `lock`. AFAICT from the code, that `lock` is there less to protect the supervisors from each other and more to ensure that while the manager itself is being started or stopped, no other action should occur. Changing the usage of this `lock` can have negative effects.
For example, what would happen when the `SupervisorManager` is stopping and a new supervisor is submitted? You could try using `globalLock` on some of the operations inside `createOrUpdateSupervisorInternal()` but that could still lead to a weird state where the stopping thread is say, removing stuff from the `autoscalers` map but another thread keeps adding to it.
A better implementation would be to maintain states of the `SupervisorManager` rather than a single `started` boolean. And while it is in `STARTING` or `STOPPING` state, every other action would have to be failed (or maybe just blocked?).
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[GitHub] [druid] AmatyaAvadhanula commented on pull request #13076: Independent Supervisor Creation/Updation/Termination
Posted by GitBox <gi...@apache.org>.
AmatyaAvadhanula commented on PR #13076:
URL: https://github.com/apache/druid/pull/13076#issuecomment-1248075809
@kfaraz thank you for the review!
> Could you share some more details regarding why these changes are needed?
A supervisor may take a long time to terminate gracefully or time out trying to do so (80s is the default).
It would be helpful to let other supervisors be created / suspended / modified / terminated without having to be blocked on operations of others', despite these not being frequent operations, as it may affect the task creation and hence the ingestion itself.
<br/>
> Maps such as autoscalers etc are already ConcurrentHashMaps and don't really need separate locks.
Thank you, I've applied this suggestion and removed the locks.
<br/>
> For example, what would happen when the SupervisorManager is stopping and a new supervisor is submitted?
This has now been handled within stop() of the SupervisorManager by synchronizing a supervisor's cleanup on the same lock used to synchronize its creation or termination.
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Re: [PR] Independent Supervisor Creation/Updation/Termination (druid)
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] commented on PR #13076:
URL: https://github.com/apache/druid/pull/13076#issuecomment-1882031514
This pull request has been marked as stale due to 60 days of inactivity.
It will be closed in 4 weeks if no further activity occurs. If you think
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write any comment. Even if closed, you can still revive the PR at any time or
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[GitHub] [druid] lgtm-com[bot] commented on pull request #13076: Independent Supervisor Creation/Updation/Termination
Posted by GitBox <gi...@apache.org>.
lgtm-com[bot] commented on PR #13076:
URL: https://github.com/apache/druid/pull/13076#issuecomment-1245198069
This pull request **introduces 3 alerts** when merging a901acfe800656d0714e7eaf2456c853ae849cee into 08d6aca52865ab7bcbf75e16c4ca153bd3ca06f3 - [view on LGTM.com](https://lgtm.com/projects/g/apache/druid/rev/pr-7a904edf4d76e7a90a6f245a9e5515a0d0ce86a1)
**new alerts:**
* 3 for Dereferenced variable may be null
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Re: [PR] Independent Supervisor Creation/Updation/Termination (druid)
Posted by "github-actions[bot] (via GitHub)" <gi...@apache.org>.
github-actions[bot] closed pull request #13076: Independent Supervisor Creation/Updation/Termination
URL: https://github.com/apache/druid/pull/13076
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