[READ-ONLY] Mirror of https://github.com/vitest-dev/vitest. Next generation testing framework powered by Vite.
vitest.dev
test
testing-tools
vite
chore: drop the temporary benchmark harness and the env escape hatch
Vladimir Sheremet
(Jul 9, 2026, 3:01 PM +0200)
7e5d0937
8f93c1b4
+1
-170
-122
scripts/bench-adaptive.mjs
-122
scripts/bench-adaptive.mjs
···
1
-
// TEMPORARY (PR-only): A/B benchmark for the pool's adaptive worker scaling.
2
-
// Generates small fixtures inside the repo (so `vitest` resolves from the
3
-
// workspace root), then interleaves reps of VITEST_POOL_ADAPTIVE=1 (default)
4
-
// vs VITEST_POOL_ADAPTIVE=0 (previous behavior) within every cell.
5
-
import { spawnSync } from 'node:child_process'
6
-
import { mkdirSync, rmSync, writeFileSync } from 'node:fs'
7
-
import { join } from 'node:path'
8
-
9
-
const REPO = new URL('..', import.meta.url).pathname.replace(/^\/(\w:)/, '$1')
10
-
const CLI = join(REPO, 'packages/vitest/dist/cli.js')
11
-
const REPS = Number(process.env.BENCH_REPS || 5)
12
-
13
-
const FIXTURE_ROOT = join(REPO, '.bench-adaptive')
14
-
15
-
function generateFixture(name, fileCount) {
16
-
const root = join(FIXTURE_ROOT, name)
17
-
rmSync(root, { recursive: true, force: true })
18
-
mkdirSync(join(root, 'test'), { recursive: true })
19
-
mkdirSync(join(root, 'src'), { recursive: true })
20
-
for (let i = 0; i < 5; i++) {
21
-
writeFileSync(join(root, `src/m${i}.ts`), `
22
-
export function m${i}(x: number): number {
23
-
return x * ${i + 2}
24
-
}
25
-
`)
26
-
}
27
-
for (let t = 0; t < fileCount; t++) {
28
-
writeFileSync(join(root, `test/t${t}.test.ts`), `
29
-
import { expect, test } from 'vitest'
30
-
import { m${t % 5} } from '../src/m${t % 5}'
31
-
32
-
test('t${t} computes', () => {
33
-
expect(m${t % 5}(${t})).toBe(${t * ((t % 5) + 2)})
34
-
})
35
-
test('t${t} strings', () => {
36
-
expect('t${t}'.repeat(2)).toContain('t${t}')
37
-
})
38
-
`)
39
-
}
40
-
writeFileSync(join(root, 'vitest.config.ts'), `
41
-
import { defineConfig } from 'vitest/config'
42
-
43
-
export default defineConfig({
44
-
cacheDir: 'node_modules/.vite-bench',
45
-
test: {
46
-
watch: false,
47
-
environment: 'node',
48
-
pool: process.env.BENCH_POOL as 'forks',
49
-
isolate: process.env.BENCH_ISOLATE !== '0',
50
-
reporters: [['default', { summary: false }]],
51
-
},
52
-
})
53
-
`)
54
-
return root
55
-
}
56
-
57
-
function runOnce(root, pool, isolate, adaptive) {
58
-
const env = {
59
-
...process.env,
60
-
NO_COLOR: '1',
61
-
CI: 'true',
62
-
BENCH_POOL: pool,
63
-
BENCH_ISOLATE: isolate ? '1' : '0',
64
-
VITEST_POOL_ADAPTIVE: adaptive ? '1' : '0',
65
-
}
66
-
const start = performance.now()
67
-
const result = spawnSync(process.execPath, [CLI, 'run', '--root', root], {
68
-
env,
69
-
encoding: 'utf-8',
70
-
maxBuffer: 64 * 1024 * 1024,
71
-
})
72
-
const wall = performance.now() - start
73
-
if (result.status !== 0) {
74
-
console.error(`FAILED pool=${pool} isolate=${isolate} adaptive=${adaptive}`)
75
-
console.error(result.stdout?.slice(-2000))
76
-
console.error(result.stderr?.slice(-2000))
77
-
process.exit(1)
78
-
}
79
-
return wall
80
-
}
81
-
82
-
function median(values) {
83
-
const sorted = [...values].sort((a, b) => a - b)
84
-
return sorted[sorted.length >> 1]
85
-
}
86
-
87
-
const small = generateFixture('small', 40)
88
-
const large = generateFixture('large', 160)
89
-
90
-
const CELLS = [
91
-
{ label: 'forks isolate:false 40 files', root: small, pool: 'forks', isolate: false },
92
-
{ label: 'forks isolate:true 40 files', root: small, pool: 'forks', isolate: true },
93
-
{ label: 'forks isolate:false 160 files', root: large, pool: 'forks', isolate: false },
94
-
{ label: 'threads isolate:false 40 files', root: small, pool: 'threads', isolate: false },
95
-
]
96
-
97
-
const rows = []
98
-
for (const cell of CELLS) {
99
-
// warm up the transform cache once so the reps measure scheduling, not
100
-
// first-transform noise
101
-
runOnce(cell.root, cell.pool, cell.isolate, true)
102
-
const adaptive = []
103
-
const fixed = []
104
-
for (let rep = 0; rep < REPS; rep++) {
105
-
adaptive.push(runOnce(cell.root, cell.pool, cell.isolate, true))
106
-
fixed.push(runOnce(cell.root, cell.pool, cell.isolate, false))
107
-
console.error(`${cell.label} rep${rep}: adaptive=${adaptive.at(-1) | 0}ms fixed=${fixed.at(-1) | 0}ms`)
108
-
}
109
-
const adaptiveMed = median(adaptive)
110
-
const fixedMed = median(fixed)
111
-
const delta = ((adaptiveMed - fixedMed) / fixedMed * 100).toFixed(1)
112
-
rows.push(`| ${cell.label} | ${fixedMed | 0}ms | ${adaptiveMed | 0}ms | ${delta}% |`)
113
-
}
114
-
115
-
console.log('\n### Adaptive pool scaling A/B (median of %d, lower is better)\n', REPS)
116
-
console.log('| cell | fixed (old) | adaptive | Δ |')
117
-
console.log('|---|---:|---:|---:|')
118
-
for (const row of rows) {
119
-
console.log(row)
120
-
}
121
-
122
-
rmSync(FIXTURE_ROOT, { recursive: true, force: true })
-44
.github/workflows/bench-adaptive.yml
-44
.github/workflows/bench-adaptive.yml
···
1
-
# TEMPORARY (PR-only, removed before merge): measures the pool's adaptive
2
-
# worker scaling on/off on the platforms where worker spawn costs differ the
3
-
# most. Windows is the interesting one — process spawn is several times more
4
-
# expensive there.
5
-
name: bench-adaptive
6
-
7
-
on:
8
-
pull_request:
9
-
paths:
10
-
- .github/workflows/bench-adaptive.yml
11
-
- scripts/bench-adaptive.mjs
12
-
- 'packages/vitest/src/node/pools/**'
13
-
workflow_dispatch:
14
-
15
-
permissions: {}
16
-
17
-
jobs:
18
-
bench:
19
-
name: 'Bench: adaptive scaling, ${{ matrix.os }}'
20
-
runs-on: ${{ matrix.os }}
21
-
timeout-minutes: 40
22
-
23
-
strategy:
24
-
matrix:
25
-
os: [windows-latest, ubuntu-latest]
26
-
fail-fast: false
27
-
28
-
steps:
29
-
- uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
30
-
with:
31
-
persist-credentials: false
32
-
33
-
- uses: ./.github/actions/setup-and-cache
34
-
with:
35
-
node-version: 24
36
-
37
-
- name: Install
38
-
run: pnpm i --filter '!docs'
39
-
40
-
- name: Build
41
-
run: pnpm run build
42
-
43
-
- name: Bench
44
-
run: node scripts/bench-adaptive.mjs
+1
-4
packages/vitest/src/node/pools/pool.ts
+1
-4
packages/vitest/src/node/pools/pool.ts
···
12
12
13
13
const WORKER_START_TIMEOUT = 90_000
14
14
15
-
// escape hatch while the adaptive worker scaling is validated across platforms
16
-
const isAdaptiveScalingEnabled = process.env.VITEST_POOL_ADAPTIVE !== '0'
17
-
18
15
interface Options {
19
16
distPath: string
20
17
teardownTimeout: number
···
92
89
return
93
90
}
94
91
95
-
if (isAdaptiveScalingEnabled && !this.canScheduleNext()) {
92
+
if (!this.canScheduleNext()) {
96
93
// re-evaluated when the in-flight worker start settles or a task
97
94
// finishes — both end with another `schedule()` call
98
95
return