feat: preference to limit thread count of the LS

Added a new preference (`arduino.language.asyncWorkers`) to control the
number of async workers used by `clangd`.
Users can use fine tune the `clangd` thread count to overcome excessive
CPU usage.

Ref: arduino/arduino-language-server#177
Signed-off-by: Akos Kitta <[email protected]>

Author: Akos Kitta

arduino-ide-extension/package.json

@@ -169,13 +169,13 @@
   ],
   "arduino": {
     "arduino-cli": {
-      "version": "0.35.1"
+      "version": "0.35.2"
     },
     "arduino-fwuploader": {
       "version": "2.4.1"
     },
     "arduino-language-server": {
-      "version": "0.7.5"
+      "version": "0.7.6"
     },
     "clangd": {
       "version": "14.0.0"

arduino-ide-extension/src/browser/arduino-preferences.ts

@@ -54,6 +54,10 @@ export function isMonitorWidgetDockPanel(
   return arg === 'bottom' || arg === 'right';
 }
 
+export const defaultAsyncWorkers = 0 as const;
+export const minAsyncWorkers = defaultAsyncWorkers;
+export const maxAsyncWorkers = 8 as const;
+
 type StrictPreferenceSchemaProperties<T extends object> = {
   [p in keyof T]: PreferenceSchemaProperty;
 };
@@ -79,6 +83,16 @@ const properties: ArduinoPreferenceSchemaProperties = {
     ),
     default: false,
   },
+  'arduino.language.asyncWorkers': {
+    type: 'number',
+    description: nls.localize(
+      'arduino/preferences/language.asyncWorkers',
+      'Number of async workers used by the Arduino Language Server (clangd). Background index also uses this many workers. The minimum value is 0, and the maximum is 8. When it is 0, the language server uses all available cores. The default value is 0.'
+    ),
+    minimum: minAsyncWorkers,
+    maximum: maxAsyncWorkers,
+    default: defaultAsyncWorkers,
+  },
   'arduino.compile.verbose': {
     type: 'boolean',
     description: nls.localize(
@@ -298,6 +312,7 @@ export const ArduinoConfigSchema: PreferenceSchema = {
 export interface ArduinoConfiguration {
   'arduino.language.log': boolean;
   'arduino.language.realTimeDiagnostics': boolean;
+  'arduino.language.asyncWorkers': number;
   'arduino.compile.verbose': boolean;
   'arduino.compile.experimental': boolean;
   'arduino.compile.revealRange': ErrorRevealStrategy;

arduino-ide-extension/src/browser/contributions/ino-language.ts

@@ -6,19 +6,24 @@ import { inject, injectable } from '@theia/core/shared/inversify';
 import { Mutex } from 'async-mutex';
 import {
   ArduinoDaemon,
-  assertSanitizedFqbn,
   BoardIdentifier,
   BoardsService,
   ExecutableService,
+  assertSanitizedFqbn,
   isBoardIdentifierChangeEvent,
   sanitizeFqbn,
 } from '../../common/protocol';
-import { CurrentSketch } from '../sketches-service-client-impl';
+import {
+  defaultAsyncWorkers,
+  maxAsyncWorkers,
+  minAsyncWorkers,
+} from '../arduino-preferences';
+import { BoardsDataStore } from '../boards/boards-data-store';
 import { BoardsServiceProvider } from '../boards/boards-service-provider';
 import { HostedPluginEvents } from '../hosted/hosted-plugin-events';
 import { NotificationCenter } from '../notification-center';
+import { CurrentSketch } from '../sketches-service-client-impl';
 import { SketchContribution, URI } from './contribution';
-import { BoardsDataStore } from '../boards/boards-data-store';
 
 interface DaemonAddress {
   /**
@@ -76,6 +81,10 @@ interface StartLanguageServerParams {
    * If `true`, the logging is not forwarded to the _Output_ view via the language client.
    */
   readonly silentOutput?: boolean;
+  /**
+   * Number of async workers used by `clangd`. Background index also uses this many workers. If `0`, `clangd` uses all available cores. It's `0` by default.
+   */
+  readonly jobs?: number;
 }
 
 /**
@@ -137,6 +146,7 @@ export class InoLanguage extends SketchContribution {
             switch (preferenceName) {
               case 'arduino.language.log':
               case 'arduino.language.realTimeDiagnostics':
+              case 'arduino.language.asyncWorkers':
                 forceRestart();
             }
           }
@@ -168,9 +178,12 @@ export class InoLanguage extends SketchContribution {
         }
       }),
     ]);
-    this.boardsServiceProvider.ready.then(() =>
-      start(this.boardsServiceProvider.boardsConfig.selectedBoard)
-    );
+    Promise.all([
+      this.boardsServiceProvider.ready,
+      this.preferences.ready,
+    ]).then(() => {
+      start(this.boardsServiceProvider.boardsConfig.selectedBoard);
+    });
   }
 
   onStop(): void {
@@ -230,11 +243,16 @@ export class InoLanguage extends SketchContribution {
         // NOOP
         return;
       }
-      this.logger.info(`Starting language server: ${fqbnWithConfig}`);
       const log = this.preferences.get('arduino.language.log');
       const realTimeDiagnostics = this.preferences.get(
         'arduino.language.realTimeDiagnostics'
       );
+      const jobs = this.getAsyncWorkersPreferenceSafe();
+      this.logger.info(
+        `Starting language server: ${fqbnWithConfig}${
+          jobs ? ` (async worker count: ${jobs})` : ''
+        }`
+      );
       let currentSketchPath: string | undefined = undefined;
       if (log) {
         const currentSketch = await this.sketchServiceClient.currentSketch();
@@ -273,6 +291,7 @@ export class InoLanguage extends SketchContribution {
           },
           realTimeDiagnostics,
           silentOutput: true,
+          jobs,
         }),
       ]);
     } catch (e) {
@@ -283,6 +302,21 @@ export class InoLanguage extends SketchContribution {
       release();
     }
   }
+  // The Theia preference UI validation is bogus.
+  // To restrict the number of jobs to a valid value.
+  private getAsyncWorkersPreferenceSafe(): number {
+    const jobs = this.preferences.get(
+      'arduino.language.asyncWorkers',
+      defaultAsyncWorkers
+    );
+    if (jobs < minAsyncWorkers) {
+      return minAsyncWorkers;
+    }
+    if (jobs > maxAsyncWorkers) {
+      return maxAsyncWorkers;
+    }
+    return jobs;
+  }
 
   private async start(
     params: StartLanguageServerParams

electron-app/package.json

@@ -196,7 +196,7 @@
   "theiaPlugins": {
     "vscode-builtin-cpp": "https://open-vsx.org/api/vscode/cpp/1.52.1/file/vscode.cpp-1.52.1.vsix",
     "vscode-arduino-api": "https://github.com/dankeboy36/vscode-arduino-api/releases/download/0.1.2/vscode-arduino-api-0.1.2.vsix",
-    "vscode-arduino-tools": "https://downloads.arduino.cc/vscode-arduino-tools/vscode-arduino-tools-0.1.1.vsix",
+    "vscode-arduino-tools": "https://github.com/kittaakos/vscode-arduino-tools/raw/arduino/arduino-language-server%23177-VSIX/build-artifacts/vscode-arduino-tools-0.1.2.vsix",
     "vscode-builtin-json": "https://open-vsx.org/api/vscode/json/1.46.1/file/vscode.json-1.46.1.vsix",
     "vscode-builtin-json-language-features": "https://open-vsx.org/api/vscode/json-language-features/1.46.1/file/vscode.json-language-features-1.46.1.vsix",
     "cortex-debug": "https://downloads.arduino.cc/marus25.cortex-debug/marus25.cortex-debug-1.5.1.vsix",

i18n/en.json

@@ -385,6 +385,7 @@
       "invalid.editorFontSize": "Invalid editor font size. It must be a positive integer.",
       "invalid.sketchbook.location": "Invalid sketchbook location: {0}",
       "invalid.theme": "Invalid theme.",
+      "language.asyncWorkers": "Number of async workers used by the Arduino Language Server (clangd). Background index also uses this many workers. The minimum value is 0, and the maximum is 8. When it is 0, the language server uses all available cores. The default value is 0.",
       "language.log": "True if the Arduino Language Server should generate log files into the sketch folder. Otherwise, false. It's false by default.",
       "language.realTimeDiagnostics": "If true, the language server provides real-time diagnostics when typing in the editor. It's false by default.",
       "manualProxy": "Manual proxy configuration",