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https://issues.apache.org/jira/browse/FLINK-33668?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Weijie Guo resolved FLINK-33668.
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Fix Version/s: 1.20.0
(was: 1.19.0)
Resolution: Done
master(1.20) via 4171b980717e5dc313d781210a5bbfd35449ee50.
> Decoupling Shuffle network memory and job topology
> --------------------------------------------------
>
> Key: FLINK-33668
> URL: https://issues.apache.org/jira/browse/FLINK-33668
> Project: Flink
> Issue Type: Improvement
> Components: Runtime / Network
> Reporter: Jiang Xin
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.20.0
>
>
> With FLINK-30469 and FLINK-31643, we have decoupled the shuffle network
> memory and the parallelism of tasks by limiting the number of buffers for
> each InputGate and ResultPartition in Hybrid Shuffle. However, when a task
> contains multiple ResultPartitions or many shuffle tasks are running
> simultaneously on the same TaskManager, "Insufficient number of network
> buffers" errors would still occur. This usually happens when Slot Sharing
> Group is enabled or a TaskManager contains multiple slots.
> We want to make sure that the TaskManager does not encounter "Insufficient
> number of network buffers" even if there are dozens of InputGates and
> ResultPartitions running on the same TaskManager simultaneously. I have given
> this some thought, and here is my rough proposal.
> 1. InputGate or ResultPartition only apply for buffers from LocalBufferPool,
> which means that InputGate will no longer ask for exclusive buffers from
> NetworkBufferPool directly.
> 2. When creating a LocalBufferPool, we need to specify the maximum, minimum,
> and expected number of buffers. Whenever a new LBP is created or destroyed, a
> redistribution will occur, to adjust the buffer count of all LocalBufferPools
> using the expected value as a weight and between the minimum and maximum
> values. According to the test, the minimum value can be set to 4 to make the
> Flink Job work despite the possibility of lower performance. With this
> minimum value, a task with 20 shuffle edges needs only 5MB of memory to avoid
> "insufficient network buffer" error.
> 3. During runtime, InputGate and ResultPartition both calculate the number of
> buffers used by their internal data structures based on the pool size of
> their corresponding LocalBufferPool, such as the exclusive buffer queue of
> InputGate and BufferAccumulator of ResultPartition.
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