fix: Restart a shut down worker before sending it a task. (jestjs#14015)

e2e/__tests__/__snapshots__/workerRestartBeforeSend.test.ts.snap

@@ -0,0 +1,9 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`all 3 test files should complete 1`] = `
+"Test Suites: 1 failed, 2 passed, 3 total
+Tests:       2 passed, 2 total
+Snapshots:   0 total
+Time:        <<REPLACED>>
+Ran all test suites."
+`;

e2e/__tests__/workerRestartBeforeSend.test.ts

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {extractSummary} from '../Utils';
+import runJest from '../runJest';
+
+it('all 3 test files should complete', () => {
+  const result = runJest('worker-restart-before-send');
+  const {summary} = extractSummary(result.stderr);
+  expect(summary).toMatchSnapshot();
+});

e2e/worker-restart-before-send/__tests__/test1.js

@@ -0,0 +1,15 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('jest-worker killed', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});
+
+setTimeout(() => {
+  // Self-kill process.
+  process.kill(process.pid);
+}, 50);

e2e/worker-restart-before-send/__tests__/test2.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('basic test', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});

e2e/worker-restart-before-send/__tests__/test3.js

@@ -0,0 +1,10 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+test('basic test', async () => {
+  await new Promise(resolve => setTimeout(resolve, 100));
+});

e2e/worker-restart-before-send/package.json

@@ -0,0 +1,6 @@
+{
+  "jest": {
+    "maxWorkers": 2,
+    "testSequencer": "./testSequencer.js"
+  }
+}

e2e/worker-restart-before-send/testSequencer.js

@@ -0,0 +1,22 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+const Sequencer = require('@jest/test-sequencer').default;
+
+// Ensure that test1.js runs first.
+class CustomSequencer extends Sequencer {
+  sort(tests) {
+    // Test structure information
+    // https://github.com/facebook/jest/blob/6b8b1404a1d9254e7d5d90a8934087a9c9899dab/packages/jest-runner/src/types.ts#L17-L21
+    const copyTests = Array.from(tests);
+    return copyTests.sort((testA, testB) => (testA.path > testB.path ? 1 : -1));
+  }
+}
+
+module.exports = CustomSequencer;

packages/jest-worker/src/WorkerPool.ts

@@ -24,6 +24,7 @@ class WorkerPool extends BaseWorkerPool implements WorkerPoolInterface {
     onEnd: OnEnd,
     onCustomMessage: OnCustomMessage,
   ): void {
+    this.restartWorkerIfShutDown(workerId);
     this.getWorkerById(workerId).send(request, onStart, onEnd, onCustomMessage);
   }
 

packages/jest-worker/src/base/BaseWorkerPool.ts

@@ -13,6 +13,7 @@ import {
   WorkerInterface,
   WorkerOptions,
   WorkerPoolOptions,
+  WorkerStates,
 } from '../types';
 
 // How long to wait for the child process to terminate
@@ -28,9 +29,11 @@ export default class BaseWorkerPool {
   private readonly _stdout: NodeJS.ReadableStream;
   protected readonly _options: WorkerPoolOptions;
   private readonly _workers: Array<WorkerInterface>;
+  private readonly _workerPath: string;
 
   constructor(workerPath: string, options: WorkerPoolOptions) {
     this._options = options;
+    this._workerPath = workerPath;
     this._workers = new Array(options.numWorkers);
 
     const stdout = mergeStream();
@@ -84,6 +87,24 @@ export default class BaseWorkerPool {
     return this._workers[workerId];
   }
 
+  restartWorkerIfShutDown(workerId: number): void {
+    if (this._workers[workerId].state === WorkerStates.SHUT_DOWN) {
+      const {forkOptions, maxRetries, resourceLimits, setupArgs} =
+        this._options;
+      const workerOptions: WorkerOptions = {
+        forkOptions,
+        idleMemoryLimit: this._options.idleMemoryLimit,
+        maxRetries,
+        resourceLimits,
+        setupArgs,
+        workerId,
+        workerPath: this._workerPath,
+      };
+      const worker = this.createWorker(workerOptions);
+      this._workers[workerId] = worker;
+    }
+  }
+
   createWorker(_workerOptions: WorkerOptions): WorkerInterface {
     throw Error('Missing method createWorker in WorkerPool');
   }