2.7 KiB
PR #278: build placement date keys directly
Measured on 2026-10-16, starting from PR #278 at cbde23f.
The unchanged benchmark finished in 299.372 seconds before this change, leaving
only 0.628 seconds before its 300-second timeout. A separate loaded-year CPU
profile attributed 8.27 of 66.57 seconds to placementTieKey, including its
callees. That function runs when looking up cached calendar observations and
when comparing final placement dates.
The one-line optimization sorts the placement map's date keys directly, using native string sorting. It removes the intermediate placement-to-date array and the comparison callback. Every placement map entry is keyed by its placement's date, and native string sorting preserves the existing lexical date order, so the resulting keys are identical. Search choices and scoring are unchanged.
Before and after
Both runs used Node 24.18.0, Bun 1.3.14, Vitest 5.0.3, the same local machine, and the exact command below. No other test, build or profiling workload ran alongside either measurement.
NODE_OPTIONS=--max-old-space-size=2048 timeout 300s bunx vitest run src/app/benchmark/leave-planner-benchmark.spec.ts --maxWorkers=1
All seven warm-ups, fourteen measured calculations, the typed-obligation precheck, fixtures and assertions remain unchanged. Coverage is disabled for this command.
| Measurement | Before | After |
|---|---|---|
| Entire command, external wall time | 299.372 s | 268.573 s |
| Benchmark test | 293.620 s | 263.265 s |
| Loaded year, mean of two measured calculations | 76.649 s | 67.747 s |
| Headroom before timeout | 0.628 s | 31.427 s |
The entire command was 10.3% faster in this before-and-after pair. Both runs completed successfully, and every repeated scenario remained deterministic. These are local measurements; Gitea runner performance still needs confirmation.
Correctness checks
Complete outcomes, stable explanations and final-state snapshots match the baseline for all seven scenarios. These separate comparisons ran alongside functional checks; their diagnostic timings are not used in the table above.
The functional coverage suite passes all 635 tests across 33 files. Application
and spec type checks, lint, source formatting and git diff --check also pass.
No browser timing run or live CI rerun was performed for this change.
The profiling runner and full protocol logs are retained in
/tmp/vac-opt278-measure. The original diagnostic reproduction is documented in
issue-78.md.