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@wanglijie95 wanglijie95 commented Jan 11, 2023

What is the purpose of the change

In the current implementation(FLINK-25035), when the upstream vertex parallelism is much greater than the downstream vertex parallelism, it may lead to a large number of channels in the downstream tasks(for example, A -> B, all to all edge, max parallelism is 1000. If parallelism of A is 1000, parallelism of B is decided to be 1, then the only subtask of B will consume 1000 * 1000 subpartitions), resulting in a large overhead for processing channels.

In this ticket, we temporarily address this issue by limiting the max number of subpartitons consumed by each downstream task. The ultimate solution should be to support single channel consume multiple subpartitons.

Verifying this change

Unit tests:
DefaultVertexParallelismAndInputInfosDeciderTest#testEvenlyDistributeDataWithMaxSubpartitionLimitation
DefaultVertexParallelismAndInputInfosDeciderTest#testDecideParallelismWithMaxSubpartitionLimitation

Does this pull request potentially affect one of the following parts:

  • Dependencies (does it add or upgrade a dependency): (no)
  • The public API, i.e., is any changed class annotated with @Public(Evolving): (no)
  • The serializers: (no)
  • The runtime per-record code paths (performance sensitive): (no)
  • Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: (no)
  • The S3 file system connector: (no)

Documentation

  • Does this pull request introduce a new feature? (no)
  • If yes, how is the feature documented? (not applicable)

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flinkbot commented Jan 11, 2023

CI report:

Bot commands The @flinkbot bot supports the following commands:
  • @flinkbot run azure re-run the last Azure build

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@zhuzhurk zhuzhurk left a comment

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Thanks for opening this PR. @wanglijie95
I only have one comment regarding the first commit.

@wanglijie95
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@zhuzhurk Thanks for review, I 've addressed the comment, please take a look.

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LGTM.

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@flinkbot run azure

@wanglijie95 wanglijie95 deleted the FLINK-30631 branch January 16, 2023 09:14
chucheng92 pushed a commit to chucheng92/flink that referenced this pull request Feb 3, 2023
akkinenivijay pushed a commit to krisnaru/flink that referenced this pull request Feb 11, 2023
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3 participants