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https://issues.apache.org/jira/browse/FLINK-10661?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhijiang closed FLINK-10661.
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Resolution: Won't Fix
Close now until it is really needed.
> Initial credit should be configured in a separate parameter
> -----------------------------------------------------------
>
> Key: FLINK-10661
> URL: https://issues.apache.org/jira/browse/FLINK-10661
> Project: Flink
> Issue Type: Sub-task
> Components: Runtime / Network
> Affects Versions: 1.5.4, 1.6.1
> Reporter: Zhijiang
> Assignee: Zhijiang
> Priority: Minor
>
> In credit-based network flow control, the required credits on receiver side
> are calculated by backlog plus initial credit which is equal to the value in
> parameter {{taskmanager.network.memory.buffers-per-channel}}. We plus the
> initial credit as backlog overhead in order to decrease the possibility of
> waiting credits on sender side. The best result is concurrent work between
> sender and receiver, not block each other.
>
> We found a bad case in some rebalance or rescale scenarios, the outqueue
> usage reaches 100% on sender side, but the inqueue usage is about 50% or
> less. That means the credit announcement is not enough for sender side
> although there are still many free credit resources on receiver side. So it
> is not reasonable resulting in wasting resources.
>
> It would be better if we can adjust the credit overhead to debug the
> performance online. And it needs another separate parameter to define initial
> credit not messed with {{taskmanager.network.memory.buffers-per-channel}}
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