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[FLINK-40904][runtime] Detect FORWARD parallelism mismatch with the actual consumer parallelism - #29374
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…artitionDeploymentDescriptor A task can only see the number of subpartitions of its outputs, which is not the consumer parallelism on a POINTWISE edge. Pass the parallelism of the consuming job vertices through ResultPartitionDeploymentDescriptor and expose it via Environment#getWriterConsumerParallelism. No behavior change.
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| } | ||
| }); | ||
| harness.streamMockEnvironment.setOutputs(newOutputs); | ||
| harness.streamMockEnvironment.setWriterConsumerParallelism(2); |
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Should we also test for downscale? (2->1)
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Thanks for the review!
Added, and can be checked from https://github.com/apache/flink/compare/7c587b2fafda4c98574c554d346c1e56c3dfd2d2..c94c182fca54430cee83abc3183879af18eb8086
…ctual consumer parallelism The FORWARD-to-REBALANCE downgrade compared the producer parallelism with the number of subpartitions, which is not the consumer parallelism on a POINTWISE edge. Equal parallelism > 1 was taken as a mismatch, and N -> M with N > 1 could go undetected. Compare with the actual consumer parallelism instead and include both values in the log.
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What is the purpose of the change
StreamTask replaces a ForwardPartitioner with a RebalancePartitioner when the parallelism of a FORWARD edge doesn't match (FLINK-30213). The check compares the producer parallelism with the number of subpartitions, which is not the consumer parallelism on a POINTWISE edge. Equal parallelism > 1 is taken as a mismatch, and N -> M with N > 1 can go undetected (e.g. 2 -> 4 with the DefaultScheduler, where half of the consumers get no data). Found in #29272 (comment).
Brief change log
ResultPartitionDeploymentDescriptorand expose it viaEnvironment#getWriterConsumerParallelism.StreamTaskcompares the producer parallelism with it instead of the number of subpartitions, and logs both values.Verifying this change
StreamTaskTest#testForwardPartitionerIsConvertedToRebalanceOnParallelismChangesnow simulates the change via the consumer parallelism.ResultPartitionDeploymentDescriptorTestcovers the new field.Does this pull request potentially affect one of the following parts
ResultPartitionDeploymentDescriptorcarries one more int)Documentation