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https://issues.apache.org/jira/browse/SPARK-7699?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14555871#comment-14555871
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Sean Owen commented on SPARK-7699:
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Say initial = 3 and min = 1. There is no load at the start. You may start with
3 executors (ramp-down occurred after the initial executor request was
fulfilled) or 1 (ramp-down happened before the request, or the request was
successfully cancelled). This JIRA says that it should not be 1; you're saying
it might start at 3. I agree it might start at 3 but disagree with the idea
that it can't be 1.
In the short term, the right number of executors is 1; 3 executors will ramp
down to 1 soon anyway. So either of these seems like a reasonable result.
You can say, well, initial = 3 has no effect or is pointless in this situation.
That's true. There is no point in setting initial = 3 in this situation, and
the caller shouldn't do that if he/she knows there is no load. But either
actual resulting behavior seems to be fine.
I don't see a reason to artificially prevent changing from initial for a while,
and I don't think it should be scrapped since it does serve a good purpose:
when there *is* initial load, this lets you start at a much more reasonable
number of executors and increase from there rather than start from the minimum.
That's the core purpose of initialExecutors, right?
That's why I disagree with the premise of the JIRA that is has no effect, and
say that the current behavior seems correct in the no-load case assuming rapid
ramp-down is desired, and I think everyone agrees with that. That's why I'd say
this isn't a problem -- does this hold together?
> Config "spark.dynamicAllocation.initialExecutors" has no effect
> ----------------------------------------------------------------
>
> Key: SPARK-7699
> URL: https://issues.apache.org/jira/browse/SPARK-7699
> Project: Spark
> Issue Type: Bug
> Components: Spark Core
> Reporter: meiyoula
>
> spark.dynamicAllocation.minExecutors 2
> spark.dynamicAllocation.initialExecutors 3
> spark.dynamicAllocation.maxExecutors 4
> Just run the spark-shell with above configurations, the initial executor
> number is 2.
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