fix: Disable file watching when an "ENOSPC: System limit for number of

file watchers reached" error is raised.

packages/cli/src/fingerprint/fingerprintWatchCommand.ts

@@ -45,6 +45,19 @@ export default class FingerprintWatchCommand {
     }
   }
 
+  async watcherErrorFunction (error: Error) {
+    if (error.message.includes("ENOSPC: System limit for number of file watchers reached")) {
+      console.warn(error.stack);
+      console.warn("Will disable file watching. File polling will stay enabled.");
+      await this.watcher?.close();
+      this.watcher = undefined;
+      console.warn("File watching disabled.");
+    } else {
+      // let it crash if it's some other error, to learn what the error is
+      throw error;
+    }
+  };
+
   async execute() {
     this.fpQueue.process().then(() => {
       this.fpQueue.handler.checkVersion = false;
@@ -68,7 +81,8 @@ export default class FingerprintWatchCommand {
     })
       .on('add', this.added.bind(this))
       .on('change', this.changed.bind(this))
-      .on('unlink', this.removed.bind(this));
+      .on('unlink', this.removed.bind(this))
+      .on('error', error => this.watcherErrorFunction(error));
 
     const watchReady = new Promise<void>((r) => this.watcher?.once('ready', r));
 

packages/cli/tests/unit/fingerprint/fingerprintWatchCommand.spec.ts

@@ -11,6 +11,7 @@ import { once } from 'events';
 import Fingerprinter from '../../../src/fingerprint/fingerprinter';
 import { MaxMSBetween } from '../../../src/lib/eventAggregator';
 import { mkdir } from 'fs/promises';
+import { FSWatcher } from 'chokidar';
 
 jest.mock('../../../src/telemetry');
 const Telemetry = jest.mocked(OriginalTelemetry);
@@ -84,6 +85,14 @@ describe(FingerprintWatchCommand, () => {
       return verifyIndexSuccess(200, 20);
     });
 
+    it('does not raise if it hits the limit of the number of file watchers', async () => {
+      cmd = new FingerprintWatchCommand(appMapDir);
+      cmd.watcher = new FSWatcher();
+      expect(cmd.watcher).not.toBeUndefined();
+      await cmd.watcherErrorFunction(new Error("ENOSPC: System limit for number of file watchers reached"));
+      expect(cmd.watcher).toBeUndefined();
+     });
+
     describe('telemetry', () => {
       let handler: Fingerprinter;