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https://issues.apache.org/jira/browse/AURORA-1090?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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David McLaughlin reassigned AURORA-1090:
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Assignee: David McLaughlin
> Optimize or remove shard uniqueness check from StorageBackfill
> --------------------------------------------------------------
>
> Key: AURORA-1090
> URL: https://issues.apache.org/jira/browse/AURORA-1090
> Project: Aurora
> Issue Type: Task
> Components: Scheduler, Technical Debt
> Reporter: Bill Farner
> Assignee: David McLaughlin
> Priority: Critical
>
> We have noticed that during scheduler startup, the operation, there can be a
> significant amount of time spent between the following log lines:
> {noformat}
> Performing shard uniqueness sanity check.
> storage state machine transition PREPARED -> READY
> {noformat}
> Looking at what happens in the scheduler between those points, the expensive
> operation seems to be {{guaranteeShardUniqueness}}.
> This operation aims to validate the integrity of the storage, but its value
> is dubious. There are many other things that could be done to validate
> integrity, but they should probably not be done every time the scheduler
> loads its database.
> If the operation is kept, it can be dramatically optimized. It currently
> performs an O(n^2) scan of tasks, and this could trivially be reduced to
> O\(n\).
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