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perf(coverage): speed up v8 report generation (bounded-memory merge + precompiled globs) (#10506)
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Co-authored-by: Ari Perkkiö <ari.perkkio@gmail.com>
authored by
Alexandru Georoceanu
Claude Opus 4.8 (1M context)
Ari Perkkiö
and committed by
GitHub
(Jul 14, 2026, 10:39 AM +0300)
b05e5d63
ad065a7d
+41
-24
+15
-17
packages/coverage-v8/src/provider.ts
+15
-17
packages/coverage-v8/src/provider.ts
···
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import { existsSync, promises as fs } from 'node:fs'
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import { fileURLToPath } from 'node:url'
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// @ts-expect-error -- untyped
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import { mergeProcessCovs } from '@bcoe/v8-coverage'
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import { mergeScriptCovs } from '@bcoe/v8-coverage'
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import astV8ToIstanbul from 'ast-v8-to-istanbul'
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import libCoverage from 'istanbul-lib-coverage'
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import libReport from 'istanbul-lib-report'
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const start = debug.enabled ? performance.now() : 0
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const coverageMap = this.createCoverageMap()
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let merged: RawCoverage = { result: [] }
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const mergedScripts = new Map<ScriptCoverageWithOffset['url'], ScriptCoverageWithOffset>()
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const autoAttachSubprocess = this.options.autoAttachSubprocess
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await this.readCoverageFiles<RawCoverage>({
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onFileRead(coverage) {
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merged = mergeProcessCovs([merged, coverage])
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for (const script of coverage.result) {
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const previous = mergedScripts.get(script.url)
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const merged: typeof script = mergeScriptCovs(previous ? [previous, script] : [script])
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// mergeProcessCovs sometimes loses autoAttachSubprocess
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const fromExtendedContext = autoAttachSubprocess ? coverage.result.filter(r => r.isExtendedContext) : []
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const startOffset = previous?.startOffset || script.startOffset || 0
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const isExtendedContext = previous?.isExtendedContext || script.isExtendedContext
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// mergeProcessCovs sometimes loses startOffset, e.g. in vue
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merged.result.forEach((result) => {
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if (!result.startOffset) {
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const original = coverage.result.find(r => r.url === result.url)
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result.startOffset = original?.startOffset || 0
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merged.startOffset ||= startOffset
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if (autoAttachSubprocess && isExtendedContext) {
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merged.isExtendedContext = true
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}
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if (autoAttachSubprocess && !result.isExtendedContext) {
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const actual = fromExtendedContext.find(r => r.url === result.url)
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result.isExtendedContext = actual?.isExtendedContext
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}
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})
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mergedScripts.set(merged.url, merged)
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}
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},
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onFinished: async (project, environment) => {
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// Source maps can change based on projectName and transform mode.
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// Coverage transform re-uses source maps so we need to separate transforms from each other.
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const converted = await this.convertCoverage(
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merged,
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{ result: Array.from(mergedScripts.values()) },
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project,
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environment,
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)
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coverageMap.merge(converted)
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merged = { result: [] }
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mergedScripts.clear()
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},
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onDebug: debug,
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})
+26
-7
packages/vitest/src/node/coverage.ts
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packages/vitest/src/node/coverage.ts
···
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options!: ResolvedCoverageOptions
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globCache: Map<string, boolean> = new Map()
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autoUpdateMarker = '\n// __VITEST_COVERAGE_MARKER__'
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globMatchers?: { matchExclude: (file: string) => boolean; matchInclude: (file: string) => boolean }
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coverageFiles: CoverageFiles = new Map()
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pendingPromises: Promise<void>[] = []
···
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}
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const config = ctx._coverageOptions
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this.globMatchers = undefined
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this.options = {
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...coverageConfigDefaults,
···
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const relativeFilename = matchingRoot ? relative(matchingRoot, filename) : filename
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if (pm.isMatch(relativeFilename, this.options.exclude, { dot: true })) {
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const { matchExclude, matchInclude } = this.getGlobMatchers()
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if (matchExclude(relativeFilename)) {
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this.globCache.set(filename, false)
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return false
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}
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// By default `coverage.include` matches all files, except "coverage.exclude"
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const glob = this.options.include || '**'
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let included = pm.isMatch(relativeFilename, glob, {
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dot: true,
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ignore: this.options.exclude,
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})
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let included = matchInclude(relativeFilename)
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if (included && this.changedFiles) {
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included = this.changedFiles.includes(filename)
···
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this.globCache.set(filename, included)
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return included
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}
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/**
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* Compile `coverage.include`/`coverage.exclude` into reusable matchers once.
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* `picomatch.isMatch(file, patterns, options)` recompiles the patterns on
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* every call, which dominates the filtering step on large test suites.
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*/
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private getGlobMatchers(): { matchExclude: (file: string) => boolean; matchInclude: (file: string) => boolean } {
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if (!this.globMatchers) {
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const exclude = this.options.exclude
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const include = this.options.include
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this.globMatchers = {
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matchExclude: exclude.length ? pm(exclude, { dot: true }) : () => false,
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matchInclude: include ? pm(include, { dot: true, ignore: exclude }) : () => true,
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}
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}
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return this.globMatchers
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}
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private async getUntestedFilesByRoot(