Core: Pre-size row lists built from known-size collections - #17581
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Use Lists.newArrayListWithCapacity in ManifestsTable.partitionSummariesToRows and ManifestFiles to avoid intermediate ArrayList resizes when the target size is already known.
ebyhr
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Aug 10, 2026
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Looks good to me, but there are still same patterns in other places.
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Limiting the scope is perfectly acceptable, but I recommend providing an explanation of the intention in the PR description. This way, it becomes clear whether the limitation was intentional or not. |
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Two lists are allocated with the default
ArrayListcapacity and then filled with exactly one element per iteration of a loop whose bound is already known, so they resize as they grow. This pre-sizes both:ManifestsTable#partitionSummariesToRows— one row per entry insummariesManifestFiles— one pair per entry ingroupsLists.newArrayListWithCapacityis already used elsewhere in the module. Behavior-preserving.