[jira] [Closed] (FLINK-9014) Adapt BackPressureStatsTracker to work with credit-based flow control

["Piotr Nowojski (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/FLINK-9014?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Piotr Nowojski closed FLINK-9014.
---------------------------------
    Resolution: Not A Problem
      Assignee: Piotr Nowojski

This wasn't an issue. Senders with credit based flow control in case of back pressure are also blocked on `requestBufferBuilderBlocking` as it is the case for non credit base flow control.

Credit base flow controls works on one level deeper - in netty/PartitionRequestQueue. Once Credit base flow control blocks a channel, it prevents the netty from reading from blocked Subpartition. This means that writers to this subpartition will be eventually blocked on waiting for buffers (`requestBufferBuilderBlocking`).

> Adapt BackPressureStatsTracker to work with credit-based flow control
> ---------------------------------------------------------------------
>
>                 Key: FLINK-9014
>                 URL: https://issues.apache.org/jira/browse/FLINK-9014
>             Project: Flink
>          Issue Type: Sub-task
>          Components: Network, Webfrontend
>    Affects Versions: 1.5.0
>            Reporter: Nico Kruber
>            Assignee: Piotr Nowojski
>            Priority: Critical
>             Fix For: 1.5.0
>
>
> The {{BackPressureStatsTracker}} relies on sampling threads being blocked in {{LocalBufferPool#requestBufferBuilderBlocking}} to indicate backpressure but with credit-based flow control, we are also back-pressured if we did not get any credits (yet).



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