perf(allocator): increase initial chunk size from 512B to 16KB

[overlookmotel]

Repeat of #18234.

#20963 wiped all changes to bump.rs, going back to a fresh copy of bumpalo.

Re-apply changes from #18234 which were lost in the process - increasing default arena chunk size to 16 KiB, and altering try_with_min_align_and_capacity to respect the requested capacity in Bump::with_capacity.

Add a comment to try_with_min_align_and_capacity explaining why that change is required.

[overlookmotel]

• docs(allocator): fix typo in comment #20972 : 2 dependent PRs (#20973 , #20974 )
• docs(allocator): improve doc comment examples for vec2::Vec #20969
• perf(allocator): increase initial chunk size from 512B to 16KB #20968 👈 (View in Graphite)
• perf(allocator): add #[cold] to to error handling functions #20967
• docs(allocator, data_structures): correct comments #20966
• refactor(allocator): remove unnecessary pub(crate) from mod statement #20965
• fix(allocator): revert changes to get_current_chunk_footer_field_offset #20964
• refactor(allocator): use latest bumpalo as base for Bump #20963
• main

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[codspeed-hq]

Merging this PR will degrade performance by 7.1%

❌ 1 regressed benchmark
✅ 47 untouched benchmarks
⏩ 3 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	mangler[RadixUIAdoptionSection.jsx_keep_names]	18.5 µs	19.9 µs	-7.1%

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_{Comparing om/04-02-perf_allocator_increase_initial_chunk_size_from_512b_to_16kb (cdaac4a) with om/04-02-perf_allocator_add_cold_to_to_error_handling_functions (f341b81)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Copilot]

Pull request overview

Reapplies previously-lost allocator performance tweaks to oxc_allocator’s bump arena by increasing the default initial chunk size and ensuring with_capacity honors small requested capacities, with updated allocation-tracking snapshots.

Changes:

• Increase the initial arena chunk target (FIRST_ALLOCATION_GOAL) from 512B to 16KiB to reduce allocator calls.
• Update try_with_min_align_and_capacity so Bump::with_capacity(n) doesn’t allocate the new 16KiB default when n is much smaller.
• Refresh internal allocator test expectations and memory-allocation tracking snapshots to match the new behavior.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
crates/oxc_allocator/src/bump.rs	Adjusts first-chunk sizing behavior and updates a unit test to reflect deferred allocation on Bump::new().
tasks/track_memory_allocations/allocs_semantic.snap	Updates expected allocation counts for semantic tracking after allocator behavior change.
tasks/track_memory_allocations/allocs_minifier.snap	Updates expected allocation counts for minifier tracking after allocator behavior change.

[graphite-app]

Merge activity

• Apr 2, 3:08 PM UTC: overlookmotel added this pull request to the Graphite merge queue.
• Apr 2, 3:19 PM UTC: Merged by the Graphite merge queue.