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https://github.com/hanzoai/next.js.git
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Luke SandbergandGitHub
a7b04690e6
### What? When profiling is enabled (`--experimental-cpu-prof` / `--internal-trace`, or the `NEXT_CPU_PROF` / `NEXT_TURBOPACK_TRACING` env vars), Next.js writes a `.gitignore` containing `*` into `.next-profiles/` as it creates the directory. This keeps the profiling output out of git and out of the way of tools that scan the project tree. ### Why? `.next-profiles` is a sibling of `.next`, so it's intentionally *not* covered by the `.gitignore` create-next-app ships. The motivation was that profiles wouldn't bloat `.next` and wouldn't be silently ignored. But a sibling dir full of large profile/trace files turns out to be a liability: - **Ecosystem tools scan it.** Tailwind v4 aggressively auto-scans files and has opened a `trace-turbopack.bin` and crashed; Turborepo <2.8.13 hashes the file and OOMs, and >=2.8.13 fails to start `dev` watchers because reading the large trace is too slow. (workflow watchers are likely affected too.) - **Turbopack NFT globbing** can read/hash the file via overly broad `fs.read` patterns. - **Accidental commits.** Pushing a multi-GB trace would be miserable for a customer helping us debug. These have each gotten point bandaids (#94587, #94570), but the real fix preserves the original motivation: a nested `.gitignore` with `*` keeps the files off git **and** makes gitignore-respecting tools (Tailwind, Turborepo) skip the whole subtree, which resolves the scanning failures. Reverting to `.next/profiles` was the alternative; the gitignore approach keeps the existing path. ### How? - `ensureProfilesDir()` (`packages/next/src/lib/profiles-dir.ts`) creates `.next-profiles` and writes the `.gitignore` (only if absent, so user edits survive). Single source of truth. - `bin/next.ts` calls a `setupProfilesDir()` helper on build/dev/start, gated on the env vars so both the CLI flags and direct env-var usage are covered. Skipped when `NEXT_TURBOPACK_TRACING_PATH` redirects trace output. - Rust keeps `create_dir_all` as a backstop for the trace dir; the `.gitignore` is written in JS only. - Docs switched from `NEXT_TURBOPACK_TRACING=1` to `next dev --internal-trace`, and the stale `trace-turbopack` filename corrected to `trace-turbopack.bin`. <!-- NEXT_JS_LLM_PR -->
67 lines
2.3 KiB
TypeScript
67 lines
2.3 KiB
TypeScript
import { nextTestSetup, isNextDeploy } from 'e2e-utils'
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import { pathExists, readdir, readFile } from 'fs-extra'
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import { join } from 'path'
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describe('CPU Profiling - next build', () => {
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const { next, isNextDev, skipped, isTurbopack } = nextTestSetup({
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files: __dirname,
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buildCommand: 'pnpm next build --experimental-cpu-prof',
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dependencies: {},
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skipStart: true,
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skipDeployment: true,
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})
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if (skipped) return
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// CPU profiling only works with local `next build`, not dev or deploy modes
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if (isNextDev || isNextDeploy || skipped) {
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it('skip for development/deploy mode', () => {})
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return
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}
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beforeAll(async () => {
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// Run the build with CPU profiling enabled
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await next.build()
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})
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it('should write a .gitignore into .next-profiles', async () => {
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const gitignore = join(next.testDir, '.next-profiles', '.gitignore')
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expect(await pathExists(gitignore)).toBe(true)
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// `*` keeps the (potentially large) profiling output out of git and away
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// from gitignore-respecting tools that would otherwise scan it.
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expect(await readFile(gitignore, 'utf8')).toContain('*')
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})
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it('should create CPU profile files after build', async () => {
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const profileDir = join(next.testDir, '.next-profiles')
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const profileDirExists = await pathExists(profileDir)
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expect(profileDirExists).toBe(true)
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const files = await readdir(profileDir)
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const cpuProfiles = files.filter((f: string) => f.endsWith('.cpuprofile'))
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// Main profile should always exist
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expect(cpuProfiles.some((f) => f.startsWith('build-main-'))).toBe(true)
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if (isTurbopack) {
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// Turbopack mode generates: build-main, build-turbopack
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expect(cpuProfiles.length).toBe(2)
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expect(cpuProfiles.some((f) => f.startsWith('build-turbopack-'))).toBe(
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true
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)
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} else {
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// Webpack mode generates: build-main, build-webpack-client, build-webpack-server, build-webpack-edge-server
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expect(cpuProfiles.length).toBe(4)
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expect(
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cpuProfiles.some((f) => f.startsWith('build-webpack-client-'))
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).toBe(true)
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expect(
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cpuProfiles.some((f) => f.startsWith('build-webpack-server-'))
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).toBe(true)
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expect(
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cpuProfiles.some((f) => f.startsWith('build-webpack-edge-server-'))
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).toBe(true)
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}
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})
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})
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