perf: Avoid creating processing buffers beyond what is needed.#19426
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In Dart, processing buffers are sliced up from the merge buffer. For stages that do not use all processing threads -- perhaps because they do not have enough inputs -- we can be more efficient with memory by slicing the merge buffer based on the actual number of processors, not the number of processing threads. This patch addresses it by deferring the choice of how many buffers are needed until the stage actually starts executing. At that point, it knows how many processors it will create.
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FrankChen021
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I have reviewed the code for correctness, edge cases, concurrency, and integration risks; no issues found.
This is an automated review by Codex GPT-5
FrankChen021
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I have reviewed the code for correctness, edge cases, concurrency, and integration risks; no issues found.
This is an automated review by Codex GPT-5
capistrant
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May 12, 2026
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| final int sliceSize = chunk.capacity() / requestedSlices; |
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defensive check that requested slices > 0 or do we trust the upstream callers always request at least one slice?
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Added a defensive check.
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In Dart, processing buffers are sliced up from the merge buffer. For stages that do not use all processing threads -- perhaps because they do not have enough inputs -- we can be more efficient with memory by slicing the merge buffer based on the actual number of processors, not the number of processing threads.
This patch addresses it by deferring the choice of how many buffers are needed until the stage actually starts executing. At that point, it knows how many processors it will create.