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https://issues.apache.org/jira/browse/CASSANDRA-13569?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16052106#comment-16052106
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Aleksey Yeschenko commented on CASSANDRA-13569:
-----------------------------------------------
After having a more thorough look (sorry for my quick incorrect initial
suggestion), I'm still bothered by the way the patch handles cleanup of the
in-flight schedule tasks.
I made a minor alteration to use computeIfAbsent for scheduling and put clean
up logic into the scheduling Runnable. The rest of the patch is just factoring
a method out. Haven't tested any of it - my last day of vacation, running short
on time.
I won't be able to complete the review if you oppose the suggestions, though,
as I'm off to a 3-week no-Cassandra vacation. Feel free to swap a reviewer in
that case (:
> Schedule schema pulls just once per endpoint
> --------------------------------------------
>
> Key: CASSANDRA-13569
> URL: https://issues.apache.org/jira/browse/CASSANDRA-13569
> Project: Cassandra
> Issue Type: Improvement
> Components: Distributed Metadata
> Reporter: Stefan Podkowinski
> Assignee: Stefan Podkowinski
> Fix For: 3.0.x, 3.11.x, 4.x
>
>
> Schema mismatches detected through gossip will get resolved by calling
> {{MigrationManager.maybeScheduleSchemaPull}}. This method may decide to
> schedule execution of {{MigrationTask}}, but only after using a
> {{MIGRATION_DELAY_IN_MS = 60000}} delay (for reasons unclear to me).
> Meanwhile, as long as the migration task hasn't been executed, we'll continue
> to have schema mismatches reported by gossip and will have corresponding
> {{maybeScheduleSchemaPull}} calls, which will schedule further tasks with the
> mentioned delay. Some local testing shows that dozens of tasks for the same
> endpoint will eventually be executed and causing the same, stormy behavior
> for this very endpoints.
> My proposal would be to simply not schedule new tasks for the same endpoint,
> in case we still have pending tasks waiting for execution after
> {{MIGRATION_DELAY_IN_MS}}.
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