timely-util: Reduce Columnar ship size from 2 MiB to 32 KiB#37855
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timely-util: Reduce Columnar ship size from 2 MiB to 32 KiB#37855antiguru wants to merge 1 commit into
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Lower the `Column` chunk ship threshold from 2 MiB to 32 KiB by changing `SHIP_WORDS` from `1 << 18` to `1 << 12` words. 32 KiB is jemalloc's default `tcache_max`, so shipped chunks stay in the per-thread cache instead of taking the arena lock path. The builder path previously carried its own hardcoded `1 << 18` literal, duplicating the merger's `SHIP_WORDS`. Point the builder at `super::SHIP_WORDS` instead so both ship paths share a single source of truth and stay sized comparably, which the doc comment already promised. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Lower the
Columnchunk ship threshold from 2 MiB to 32 KiB.SHIP_WORDSdrops from1 << 18to1 << 12words.32 KiB is jemalloc's default
tcache_max, so shipped chunks stay in the per-thread cache instead of hitting the arena-lock path.The builder path previously duplicated the 2 MiB literal with its own hardcoded
1 << 18.It now references
super::SHIP_WORDS, so the merger and builder ship paths share one source of truth and stay sized comparably, as the doc comment already promised.This also prevents the two thresholds from silently diverging on future changes.
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