From 4480771081feb809591269fdf7fb187c71ef79f1 Mon Sep 17 00:00:00 2001
From: Geoffrey Booth <webadmin@geoffreybooth.com>
Date: Wed, 15 Nov 2023 20:39:09 -0800
Subject: [PATCH] esm: spawn only one hooks thread

---
 test/es-module/test-esm-loader-threads.mjs    | 24 +++++++++++++++++++
 test/fixtures/es-module-loaders/hooks-log.mjs | 19 +++++++++++++++
 .../fixtures/es-module-loaders/worker-log.mjs |  3 +++
 .../es-module-loaders/workers-spawned.mjs     |  7 ++++++
 4 files changed, 53 insertions(+)
 create mode 100644 test/es-module/test-esm-loader-threads.mjs
 create mode 100644 test/fixtures/es-module-loaders/hooks-log.mjs
 create mode 100644 test/fixtures/es-module-loaders/worker-log.mjs
 create mode 100644 test/fixtures/es-module-loaders/workers-spawned.mjs

diff --git a/test/es-module/test-esm-loader-threads.mjs b/test/es-module/test-esm-loader-threads.mjs
new file mode 100644
index 00000000000000..cf59a3850df540
--- /dev/null
+++ b/test/es-module/test-esm-loader-threads.mjs
@@ -0,0 +1,24 @@
+import { spawnPromisified } from '../common/index.mjs';
+import * as fixtures from '../common/fixtures.mjs';
+import { strictEqual } from 'node:assert';
+import { execPath } from 'node:process';
+import { describe, it } from 'node:test';
+
+describe('off-thread hooks', { concurrency: true }, () => {
+  it('uses only one hooks thread to support multiple application threads', async () => {
+    const { code, signal, stdout, stderr } = await spawnPromisified(execPath, [
+      '--no-warnings',
+      '--import',
+      `data:text/javascript,${encodeURIComponent(`
+        import { register } from 'node:module';
+        register(${JSON.stringify(fixtures.fileURL('es-module-loaders/hooks-log.mjs'))});
+      `)}`,
+      fixtures.path('es-module-loaders/workers-spawned.mjs'),
+    ]);
+
+    strictEqual(stderr, '');
+    strictEqual(stdout.split('\n').filter(line => line.startsWith('initialize')).length, 1);
+    strictEqual(code, 0);
+    strictEqual(signal, null);
+  });
+});
diff --git a/test/fixtures/es-module-loaders/hooks-log.mjs b/test/fixtures/es-module-loaders/hooks-log.mjs
new file mode 100644
index 00000000000000..a5168f97a1b9c8
--- /dev/null
+++ b/test/fixtures/es-module-loaders/hooks-log.mjs
@@ -0,0 +1,19 @@
+import { writeFileSync } from 'node:fs';
+
+let initializeCount = 0;
+let resolveCount = 0;
+let loadCount = 0;
+
+export function initialize() {
+  writeFileSync(1, `initialize ${++initializeCount}\n`);
+}
+
+export function resolve(specifier, context, next) {
+  writeFileSync(1, `resolve ${++resolveCount} ${specifier}\n`);
+  return next(specifier, context);
+}
+
+export function load(url, context, next) {
+  writeFileSync(1, `load ${++loadCount} ${url}\n`);
+  return next(url, context);
+}
diff --git a/test/fixtures/es-module-loaders/worker-log.mjs b/test/fixtures/es-module-loaders/worker-log.mjs
new file mode 100644
index 00000000000000..55e6c8f3b3a763
--- /dev/null
+++ b/test/fixtures/es-module-loaders/worker-log.mjs
@@ -0,0 +1,3 @@
+import { foo } from './module-named-exports.mjs';
+
+console.log(foo);
diff --git a/test/fixtures/es-module-loaders/workers-spawned.mjs b/test/fixtures/es-module-loaders/workers-spawned.mjs
new file mode 100644
index 00000000000000..439847656fe13e
--- /dev/null
+++ b/test/fixtures/es-module-loaders/workers-spawned.mjs
@@ -0,0 +1,7 @@
+import { Worker } from 'worker_threads';
+
+const workerURL = new URL('./worker-log.mjs', import.meta.url);
+
+// Spawn two workers
+new Worker(workerURL);
+new Worker(workerURL);