Stefan Podkowinski commented on CASSANDRA-13569:

At this point it's probably more about personal coding preferences. What's 
bugging me a bit about your version is that you're making the assumption that 
once scheduled, the runnable will always be executed and thus will cleanup 
itself. But as tasks may get canceled, this doesn't always have to be the case. 
Looking at ScheduledExecuter, this shouldn't be a problem, but I'd rather have 
this implicitly  handled in the code to make it obvious and less brittle in 
case of potential changes in the executor behavior. But again, it's probably 
more a matter of personal coding style and both versions should work in 

> 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 

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