worker: do not emit 'exit' events during process.exit()

src/env.cc

@@ -986,6 +986,7 @@ void Environment::Exit(int exit_code) {
                         isolate(), stack_trace_limit(), StackTrace::kDetailed));
   }
   if (is_main_thread()) {
+    set_can_call_into_js(false);
     stop_sub_worker_contexts();
     DisposePlatform();
     exit(exit_code);

test/parallel/test-worker-nested-on-process-exit.js

@@ -0,0 +1,20 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const { Worker, workerData } = require('worker_threads');
+
+// Test that 'exit' events for nested Workers are not received when a Worker
+// terminates itself through process.exit().
+
+if (workerData === null) {
+  const nestedWorkerExitCounter = new Int32Array(new SharedArrayBuffer(4));
+  const w = new Worker(__filename, { workerData: nestedWorkerExitCounter });
+  w.on('exit', common.mustCall(() => {
+    assert.strictEqual(nestedWorkerExitCounter[0], 0);
+  }));
+} else {
+  const nestedWorker = new Worker('setInterval(() => {}, 100)', { eval: true });
+  // The counter should never be increased here.
+  nestedWorker.on('exit', () => workerData[0]++);
+  nestedWorker.on('online', () => process.exit());
+}

test/parallel/test-worker-on-process-exit.js

@@ -0,0 +1,22 @@
+'use strict';
+require('../common');
+const assert = require('assert');
+const { spawnSync } = require('child_process');
+const { Worker } = require('worker_threads');
+
+// Test that 'exit' events for Workers are not received when the main thread
+// terminates itself through process.exit().
+
+if (process.argv[2] !== 'child') {
+  const {
+    stdout, stderr, status
+  } = spawnSync(process.execPath, [__filename, 'child'], { encoding: 'utf8' });
+  assert.strictEqual(stderr, '');
+  assert.strictEqual(stdout, '');
+  assert.strictEqual(status, 0);
+} else {
+  const nestedWorker = new Worker('setInterval(() => {}, 100)', { eval: true });
+  // This console.log() should never fire.
+  nestedWorker.on('exit', () => console.log('exit event received'));
+  nestedWorker.on('online', () => process.exit());
+}