repl,worker: fix crash when SharedArrayBuffer disabled

benchmark/worker/atomics-wait.js

@@ -7,6 +7,10 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n }) {
+  if (typeof SharedArrayBuffer === 'undefined') {
+    throw new Error('SharedArrayBuffers must be enabled to run this benchmark');
+  }
+
   const i32arr = new Int32Array(new SharedArrayBuffer(4));
   bench.start();
   for (let i = 0; i < n; i++)

lib/internal/main/worker_thread.js

@@ -9,7 +9,7 @@ const {
   ArrayPrototypeSplice,
   ObjectDefineProperty,
   PromisePrototypeCatch,
-  globalThis: { Atomics },
+  globalThis: { Atomics, SharedArrayBuffer },
 } = primordials;
 
 const {
@@ -142,6 +142,9 @@ port.on('message', (message) => {
     const originalCwd = process.cwd;
 
     process.cwd = function() {
+      // SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
+      if (typeof SharedArrayBuffer === 'undefined') return originalCwd();
+
       const currentCounter = Atomics.load(cwdCounter, 0);
       if (currentCounter === lastCounter)
         return cachedCwd;

lib/internal/worker.js

@@ -91,7 +91,8 @@ let cwdCounter;
 
 const environmentData = new SafeMap();
 
-if (isMainThread) {
+// SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
+if (isMainThread && typeof SharedArrayBuffer !== 'undefined') {
   cwdCounter = new Uint32Array(new SharedArrayBuffer(4));
   const originalChdir = process.chdir;
   process.chdir = function(path) {

test/parallel/test-worker-no-sab.js

@@ -0,0 +1,17 @@
+// Flags: --no-harmony-sharedarraybuffer
+
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const { isMainThread, Worker } = require('worker_threads');
+
+// Regression test for https://github.com/nodejs/node/issues/39717.
+
+const w = new Worker(__filename);
+
+w.on('exit', common.mustCall((status) => {
+  assert.strictEqual(status, 2);
+}));
+
+if (!isMainThread) process.exit(2);