Reduce Linux file-watcher load on large codebases by excluding nested build/dependency dirs (#7453)

Co-authored-by: Orca <help@stably.ai>

src/main/ipc/filesystem-watcher-ignore.test.ts

@@ -32,8 +32,18 @@ describe('buildParcelWatcherIgnoreOption', () => {
     }
   })
 
-  it('passes the plain list through on other platforms', () => {
-    setPlatform('linux')
-    expect(buildParcelWatcherIgnoreOption(WATCHER_IGNORE_DIRS)).toEqual(WATCHER_IGNORE_DIRS)
+  it('expands to nested globs on Linux/Windows so nested node_modules/.git are excluded', () => {
+    for (const platform of ['linux', 'win32'] as const) {
+      setPlatform(platform)
+      const option = buildParcelWatcherIgnoreOption(WATCHER_IGNORE_DIRS)
+      // @parcel/watcher resolves plain names to top-level-only absolute paths on
+      // these platforms, so nested dirs must be matched via depth-agnostic globs.
+      for (const dir of WATCHER_IGNORE_DIRS) {
+        expect(option).toContain(`**/${dir}`)
+        expect(option).toContain(`**/${dir}/**`)
+      }
+      // No plain (glob-free) entries — those would only exclude the top level.
+      expect(option.every((entry) => entry.includes('*'))).toBe(true)
+    }
   })
 })

src/main/ipc/filesystem-watcher-ignore.ts

@@ -25,7 +25,12 @@ export const MACOS_FSEVENTS_EXCLUSION_PATH_LIMIT = 8
 
 export function buildParcelWatcherIgnoreOption(ignoreDirs: readonly string[]): string[] {
   if (process.platform !== 'darwin') {
-    return [...ignoreDirs]
+    // Linux/Windows: @parcel/watcher resolves plain names to top-level-only
+    // absolute paths, so nested node_modules/.git/build/etc. (monorepos) get
+    // fully watched — on Linux that means one inotify watch per nested dir,
+    // exhausting fs.inotify.max_user_watches. Nested globs match at any depth
+    // (and **/dir still matches the top-level dir), pruning those subtrees.
+    return ignoreDirs.flatMap((dir) => [`**/${dir}`, `**/${dir}/**`])
   }
   return [
     ...ignoreDirs.slice(0, MACOS_FSEVENTS_EXCLUSION_PATH_LIMIT),

src/relay/fs-handler.ts

@@ -29,6 +29,10 @@ import { RelayStreamRegistry } from './fs-stream-registry'
 import { scanWorkspaceSpaceDirectory } from './workspace-space-scan'
 import { buildRelayCommandEnv } from './relay-command-env'
 import { assertNoClobberRenameDestinationAvailable } from '../shared/filesystem-rename-collision'
+import {
+  WATCHER_IGNORE_DIRS,
+  buildParcelWatcherIgnoreOption
+} from '../main/ipc/filesystem-watcher-ignore'
 
 type WatchState = {
   rootPath: string
@@ -408,7 +412,9 @@ export class FsHandler {
           }))
           this.dispatcher.notify('fs.changed', { events: mapped })
         },
-        { ignore: ['.git', 'node_modules', 'dist', 'build', '.next', '.cache', '__pycache__'] }
+        // Why: align remote-Linux watchers with the shared nested-glob exclusion
+        // so nested node_modules/.git don't exhaust inotify on large codebases.
+        { ignore: buildParcelWatcherIgnoreOption(WATCHER_IGNORE_DIRS) }
       )
       watchState.unwatchFn = () => {
         void subscription.unsubscribe()