wsry opened a new pull request #11088: [FLINK-16012][runtime] Reduce the default number of buffers per channel from 2 to 1 URL: https://github.com/apache/flink/pull/11088 ## What is the purpose of the change To speed up checkpoint in the case of back pressure, this commit tries to reduce the amount of data in flight by reducing the default number of buffers per channel from 2 to 1. Together with the default 8 floating buffers, one buffer per channel should be enough for most cases without performance regression. And one can increase it if there are any performance issues. ## Brief change log - Reduce the default number of buffers per channel from 2 to 1 and update document. ## Verifying this change - This change is already covered by existing tests. - Performance is verified by benchmarks. ## Does this pull request potentially affect one of the following parts: - Dependencies (does it add or upgrade a dependency): (yes / **no**) - The public API, i.e., is any changed class annotated with `@Public(Evolving)`: (yes / **no**) - The serializers: (yes / **no** / don't know) - The runtime per-record code paths (performance sensitive): (yes / **no** / don't know) - Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Yarn/Mesos, ZooKeeper: (yes / **no** / don't know) - The S3 file system connector: (yes / **no** / don't know) ## Documentation - Does this pull request introduce a new feature? (yes / **no**) - If yes, how is the feature documented? (**not applicable** / docs / JavaDocs / not documented)
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