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`ng serve` crashes with `EMFILE: too many open files, watch` on macOS when `preserveSymlinks` is enabled (22.2 regression)

Aperta
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Valutazione

Difficoltà
4/5
Tempo stimato
3-5 giorni
Idoneità per principianti
48/100
Tipo di issue
Bug
Chiarezza
Specificata chiaramente
Stato di attività
Attiva
Stack tecnologico
angular, node.js, typescript
Ambito
build-system, devtools

Direzione di ricerca

Start by reading setupWatcher and createWatcher, especially the followSymlinks branch that selects chokidar, and compare the watcher behavior described for @parcel/watcher. Reproduce on macOS with preserveSymlinks: true and more than 4096 workspace directories. Done means ng serve and watch builds stay running without the EMFILE crash in that setup.

Scritto dal modello di indicizzazione a partire dal testo della issue.

Descrizione

area: @angular/build
Command

serve

Is this a regression?
  • Yes, this behavior used to work in the previous version
The previous version in which this bug was not present was

22.1.9

Description

Since 22.2.0, ng serve (and any watch build) crashes on macOS right after the first successful build when the build target sets preserveSymlinks: true and the workspace contains more than 4096 directories outside node_modules.

setupWatcher passes preserveSymlinks on as followSymlinks, and createWatcher then always picks chokidar over @parcel/watcher:

if (options?.polling || options?.followSymlinks) {
  return createChokidarWatcher(options);
}

Chokidar 5 calls fs.watch once per directory and file under the workspace root. On macOS, Node reports EMFILE as soon as one process holds more than 4096 directory watches: 4096 fs.watch calls on directories work, 4097 fail. File watches do not count towards this (50,000 worked), and ulimit -n has no influence: the crash reproduces with the hard limit at unlimited.

The error is emitted on the FSWatcher without a listener, so the dev server process exits.

In our application (about 1,250 source directories plus the packages it imports from node_modules, which chokidar also watches whole) the dev server made 33,703 fs.watch calls before crashing. With 22.1.9 and watchpack the same workspace needs 4. We depend on preserveSymlinks because plugin frontends are symlinked into src/.

Minimal Reproduction

On macOS:

npx @angular/[email protected] new emfile-repro --defaults --skip-git
cd emfile-repro
node -e "for (let i = 0; i < 4200; i++) fs.mkdirSync('many/d' + i, { recursive: true })"
npx ng config projects.emfile-repro.architect.build.options.preserveSymlinks true
npx ng serve

The server prints its local URL and exits a moment later with the error below. It keeps running with preserveSymlinks unset, or with 3000 directories instead of 4200.

Exception or Error
Error: EMFILE: too many open files, watch
    at FSWatcher._handle.onchange (node:internal/fs/watchers:267:21)
Emitted 'error' event on FSWatcher instance at:
    at FSWatcher._handleError (node_modules/chokidar/index.js:558:18)
    at NodeFsHandler._boundHandleError (node_modules/chokidar/handler.js:297:49)
    at node_modules/chokidar/handler.js:144:9
    at foreach (node_modules/chokidar/handler.js:76:9)
    at fsWatchBroadcast (node_modules/chokidar/handler.js:143:5)
    at FSWatcher.<anonymous> (node_modules/chokidar/handler.js:191:17)
    at FSWatcher.emit (node:events:509:28)
    at FSWatcher._handle.onchange (node:internal/fs/watchers:273:12) {
  errno: -24,
  syscall: 'watch',
  code: 'EMFILE',
  filename: null
}
Your Environment
Angular CLI       : 22.2.2
Angular           : 22.2.2
Node.js           : 24.18.0
Package Manager   : npm 11.16.0
Operating System  : darwin arm64 (macOS 27.0.1)

@angular/build            22.2.2
@angular/cli              22.2.2
@angular/compiler-cli     22.2.2
typescript                6.0.3
Anything else relevant?

@parcel/watcher loads and subscribes fine on the same machine, so this is not the load-failure fallback. With preserveSymlinks off the dev server holds no fs.watch handles at all. Would it be possible to keep the parcel watcher for preserveSymlinks workspaces, or to limit chokidar to the files the build actually reports instead of the whole workspace root?

Workaround: pin @angular/build to 22.1.9, or run with --watch false.

Lingua principale
TypeScript
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