[jira] [Created] (FLINK-8117) Eliminate modulo operation from RoundRobinChannelSelector and RebalancePartitioner

[Shang Yuanchun (Jira)]

Gabor Gevay created FLINK-8117:
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             Summary: Eliminate modulo operation from RoundRobinChannelSelector and RebalancePartitioner
                 Key: FLINK-8117
                 URL: https://issues.apache.org/jira/browse/FLINK-8117
             Project: Flink
          Issue Type: Improvement
          Components: Local Runtime, Streaming
            Reporter: Gabor Gevay
            Assignee: Gabor Gevay
            Priority: Minor
             Fix For: 1.5.0


Both {{RoundRobinChannelSelector}} and {{RebalancePartitioner}} use a modulo operation to wrap around when the current channel counter reaches the number of channels. Using an {{if}} would have better performance.

A division with 32 bit operands is ~25 cycles on modern Intel CPUs \[1\], but the {{if}} will be only 1-2 cycles on average, since the branch predictor can most of the time predict the condition to be false.

\[1\] http://www.agner.org/optimize/instruction_tables.pdf



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