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https://issues.apache.org/jira/browse/FLINK-20865?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Weijie Guo updated FLINK-20865:
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Affects Version/s: 2.1.0
> Prevent potential resource deadlock in fine-grained resource management
> -----------------------------------------------------------------------
>
> Key: FLINK-20865
> URL: https://issues.apache.org/jira/browse/FLINK-20865
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Coordination
> Affects Versions: 2.1.0
> Reporter: Yangze Guo
> Priority: Minor
> Labels: auto-deprioritized-major
> Fix For: 2.0.0
>
> Attachments: 屏幕快照 2021-01-06 下午2.32.57.png
>
>
> !屏幕快照 2021-01-06 下午2.32.57.png|width=954,height=288!
> The above figure demonstrates a potential case of deadlock due to scheduling
> dependency. For the given topology, initially the scheduler will request 4
> slots, for A, B, C and D. Assuming only 2 slots are available, if both slots
> are assigned to Pipeline Region 0 (as shown on the left), A and B will first
> finish execution, then C and D will be executed, and finally E will be
> executed. However, if in the beginning the 2 slots are assigned to A and C
> (as shown on the right), then neither of A and C can finish execution due to
> missing B and D consuming the data they produced.
> Currently, with coarse-grained resource management, the scheduler guarantees
> to always finish fulfilling requirements of one pipeline region before
> starting to fulfill requirements of another. That means the deadlock case
> shown on the right of the above figure can never happen.
> However, there’s no such guarantee in fine-grained resource management. Since
> resource requirements for SSGs can be different, there’s no control on which
> requirements will be fulfilled first, when there’s not enough resources to
> fulfill all the requirements. Therefore, it’s not always possible to fulfill
> one pipeline region prior to another.
> To solve this problem, we can make the scheduler defer requesting slots for
> other SSGs before requirements of the current SSG are fulfilled, for
> fine-grained resource management, at the price of more scheduling time.
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