jestjs · SimenB · Feb 22, 2023 · Feb 20, 2023 · Feb 20, 2023 · Feb 21, 2023
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -2,6 +2,8 @@
 
 ### Features
 
+- `[jest-cli, jest-config, @jest/core, jest-haste-map, @jest/reporters, jest-runner, jest-runtime, @jest/types]` Add `workerThreads` configuration option to allow using [worker threads](https://nodejs.org/dist/latest/docs/api/worker_threads.html) for parallelization ([#13939](https://github.com/facebook/jest/pull/13939))
+
 ### Fixes
 
 ### Chore & Maintenance

diff --git a/docs/CLI.md b/docs/CLI.md
@@ -502,3 +502,7 @@ In most CI environments, this is automatically handled for you.
 ### `--watchman`
 
 Whether to use [`watchman`](https://facebook.github.io/watchman/) for file crawling. Defaults to `true`. Disable using `--no-watchman`.
+
+### `--workerThreads`
+
+Whether to use [worker threads](https://nodejs.org/dist/latest/docs/api/worker_threads.html) for parallelization. [Child processes](https://nodejs.org/dist/latest/docs/api/child_process.html) are used by default.
diff --git a/docs/Configuration.md b/docs/Configuration.md
@@ -2375,3 +2375,7 @@ This option allows comments in `package.json`. Include the comment text as the v
   }
 }
 ```
+
+### `workerThreads`
+
+Whether to use [worker threads](https://nodejs.org/dist/latest/docs/api/worker_threads.html) for parallelization. [Child processes](https://nodejs.org/dist/latest/docs/api/child_process.html) are used by default.
diff --git a/packages/jest-cli/src/args.ts b/packages/jest-cli/src/args.ts
@@ -709,4 +709,10 @@ export const options: {[key: string]: Options} = {
       '--no-watchman.',
     type: 'boolean',
   },
+  workerThreads: {
+    description:
+      'Whether to use worker threads for parallelization. Child processes ' +
+      'are used by default.',
+    type: 'boolean',
+  },
 };
diff --git a/packages/jest-config/src/ValidConfig.ts b/packages/jest-config/src/ValidConfig.ts
@@ -186,6 +186,7 @@ export const initialOptions: Config.InitialOptions = {
   ],
   watchman: true,
   workerIdleMemoryLimit: multipleValidOptions(0.2, '50%'),
+  workerThreads: true,
 };
 
 export const initialProjectOptions: Config.InitialProjectOptions = {

diff --git a/packages/jest-config/src/index.ts b/packages/jest-config/src/index.ts
@@ -140,6 +140,7 @@ const groupOptions = (
     watchPlugins: options.watchPlugins,
     watchman: options.watchman,
     workerIdleMemoryLimit: options.workerIdleMemoryLimit,
+    workerThreads: options.workerThreads,
   }),
   projectConfig: Object.freeze({
     automock: options.automock,

diff --git a/packages/jest-config/src/normalize.ts b/packages/jest-config/src/normalize.ts
@@ -936,6 +936,7 @@ export default async function normalize(
       case 'watch':
       case 'watchAll':
       case 'watchman':
+      case 'workerThreads':
         value = oldOptions[key];
         break;
       case 'workerIdleMemoryLimit':

diff --git a/packages/jest-core/src/cli/index.ts b/packages/jest-core/src/cli/index.ts
@@ -157,6 +157,7 @@ const buildContextsAndHasteMaps = async (
         resetCache: !config.cache,
         watch: globalConfig.watch || globalConfig.watchAll,
         watchman: globalConfig.watchman,
+        workerThreads: globalConfig.workerThreads,
       });
       hasteMapInstances[index] = hasteMapInstance;
       return createContext(config, await hasteMapInstance.build());

diff --git a/packages/jest-haste-map/src/index.ts b/packages/jest-haste-map/src/index.ts
@@ -79,6 +79,7 @@ type Options = {
   throwOnModuleCollision?: boolean;
   useWatchman?: boolean;
   watch?: boolean;
+  workerThreads?: boolean;
 };
 
 type InternalOptions = {
@@ -103,6 +104,7 @@ type InternalOptions = {
   throwOnModuleCollision: boolean;
   useWatchman: boolean;
   watch: boolean;
+  workerThreads?: boolean;
 };
 
 type Watcher = {
@@ -267,6 +269,7 @@ class HasteMap extends EventEmitter implements IHasteMap {
       throwOnModuleCollision: !!options.throwOnModuleCollision,
       useWatchman: options.useWatchman ?? true,
       watch: !!options.watch,
+      workerThreads: options.workerThreads,
     };
     this._console = options.console || globalThis.console;
 
@@ -748,6 +751,7 @@ class HasteMap extends EventEmitter implements IHasteMap {
         this._worker = {getSha1, worker};
       } else {
         this._worker = new Worker(require.resolve('./worker'), {
+          enableWorkerThreads: this._options.workerThreads,
           exposedMethods: ['getSha1', 'worker'],
           forkOptions: {serialization: 'json'},
           maxRetries: 3,

diff --git a/packages/jest-reporters/src/CoverageReporter.ts b/packages/jest-reporters/src/CoverageReporter.ts
@@ -147,6 +147,7 @@ export default class CoverageReporter extends BaseReporter {
       worker = require('./CoverageWorker');
     } else {
       worker = new Worker(require.resolve('./CoverageWorker'), {
+        enableWorkerThreads: this._globalConfig.workerThreads,
         exposedMethods: ['worker'],
         forkOptions: {serialization: 'json'},
         maxRetries: 2,

diff --git a/packages/jest-runner/src/index.ts b/packages/jest-runner/src/index.ts
@@ -105,6 +105,7 @@ export default class TestRunner extends EmittingTestRunner {
     }
 
     const worker = new Worker(require.resolve('./testWorker'), {
+      enableWorkerThreads: this._globalConfig.workerThreads,
       exposedMethods: ['worker'],
       forkOptions: {serialization: 'json', stdio: 'pipe'},
       // The workerIdleMemoryLimit should've been converted to a number during

diff --git a/packages/jest-runtime/src/index.ts b/packages/jest-runtime/src/index.ts
@@ -79,6 +79,7 @@ type HasteMapOptions = {
   resetCache: boolean;
   watch?: boolean;
   watchman: boolean;
+  workerThreads?: boolean;
 };
 
 interface InternalModuleOptions extends Required<CallerTransformOptions> {
@@ -370,6 +371,7 @@ export default class Runtime {
       throwOnModuleCollision: config.haste.throwOnModuleCollision,
       useWatchman: options?.watchman,
       watch: options?.watch,
+      workerThreads: options?.workerThreads,
     });
   }
 

diff --git a/packages/jest-types/src/Config.ts b/packages/jest-types/src/Config.ts
@@ -326,6 +326,7 @@ export type InitialOptions = Partial<{
   watchman: boolean;
   watchPlugins: Array<string | [string, Record<string, unknown>]>;
   workerIdleMemoryLimit: number | string;
+  workerThreads: boolean;
 }>;
 
 export type SnapshotUpdateState = 'all' | 'new' | 'none';
@@ -419,6 +420,7 @@ export type GlobalConfig = {
     config: Record<string, unknown>;
   }> | null;
   workerIdleMemoryLimit?: number;
+  workerThreads?: boolean;
 };
 
 export type ProjectConfig = {
@@ -574,5 +576,6 @@ export type Argv = Arguments<
     watchman: boolean;
     watchPathIgnorePatterns: Array<string>;
     workerIdleMemoryLimit: number | string;
+    workerThreads: boolean;
   }>
 >;
-Original file line number
+Diff line change
@@ Expand Up @@
       }
     }
     ```
+    ### `workerThreads`
+    Whether to use [worker threads](https://nodejs.org/dist/latest/docs/api/worker_threads.html) for parallelization. [Child processes](https://nodejs.org/dist/latest/docs/api/child_process.html) are used by default.