[jira] [Created] (FLINK-9142) Lower the minimum number of buffers for incoming channels to 1

[Shang Yuanchun (Jira)]

Nico Kruber created FLINK-9142:
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             Summary: Lower the minimum number of buffers for incoming channels to 1
                 Key: FLINK-9142
                 URL: https://issues.apache.org/jira/browse/FLINK-9142
             Project: Flink
          Issue Type: Sub-task
          Components: Network
    Affects Versions: 1.5.0, 1.6.0
            Reporter: Nico Kruber
             Fix For: 1.5.0


Even if we make the floating buffers optional, we still require {{taskmanager.network.memory.buffers-per-channel}} number of (exclusive) buffers per incoming channel with credit-based flow control while without, the minimum was 1 and only the maximum number of buffers was influenced by this parameter.

{{taskmanager.network.memory.buffers-per-channel}} is set to {{2}} by default with the argumentation that this way we will have one buffer available for netty to process while a worker thread is processing/deserializing the other buffer. While this seems reasonable, it does increase our minimum requirements. Instead, we could probably live with {{1}} exclusive buffer and up to {{gate.getNumberOfInputChannels() * (networkBuffersPerChannel - 1) + extraNetworkBuffersPerGate}} floating buffers. That way we will have the same memory footprint as before with only slightly changed behaviour.



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