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https://issues.apache.org/jira/browse/FLINK-14536?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16963079#comment-16963079
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Till Rohrmann commented on FLINK-14536:
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This is a very good point. Tbh I'm not exactly sure why we chose {{max()}} in
{{ResourceSpec#merge}}. Maybe [~zjwang] can shed some light on the matter since
we introduced it with FLINK-5132.
I think the behaviour should be aligned. Moreover, I would have picked
{{sum()}} since {{cpuCores}} should represent the number of required cores for
one operator.
> Make clear the way to aggregate specified cpuCores resources
> ------------------------------------------------------------
>
> Key: FLINK-14536
> URL: https://issues.apache.org/jira/browse/FLINK-14536
> Project: Flink
> Issue Type: Sub-task
> Components: Runtime / Coordination
> Affects Versions: 1.10.0
> Reporter: Zhu Zhu
> Priority: Major
> Fix For: 1.10.0
>
>
> I'm raising this question because I find {{cpuCores}} in
> {{ResourceSpec#merge}} are aggregated with {{max()}}, while in
> {{ResourceProfile#merge}} it is {{sum()}}.
> This means that when calculating resources of a vertex from within operators,
> the {{cpuCores}} is the max value. While it is a sum(or subtraction in
> {{ResourceProfile#subtract}}) when dealing with shared slot bookkeeping and
> related checks.
> This is confusing to me, especially when I'm considering how to generate a
> shared slot resource spec merged from all vertices in it(see FLINK-14314).
> I'm not pretty sure if we already have a concise definition for it?
> If there is, we need to respect it and change {{ResourceSpec}} or
> {{ResourceProfile}} accordingly.
> If not, we need to decide it first before we can move on with fine grained
> resources.
> Need to mention that if we take the {{max()}} way, we need to re-consider how
> we can conduct a correct {{ResourceProfile#subtract}} regarding {{cpuCores}},
> since there is not a clear way to reverse a {{max()}} computation.
> cc [~trohrmann] [~xintongsong] [~azagrebin]
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