test: reduce flakiness of different-registry-per-thread

There was an assumption that the `WeakRef` would be kept alive but
it seems to not always be true on Windows. This commit makes sure
it's kept alive.

Signed-off-by: Antoine du Hamel <duhamelantoine1995@gmail.com>
PR-URL: nodejs#63209
Fixes: nodejs#63056
Reviewed-By: Moshe Atlow <moshe@atlow.co.il>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br>
Reviewed-By: Rafael Gonzaga <rafael.nunu@hotmail.com>
Reviewed-By: Filip Skokan <panva.ip@gmail.com>
Reviewed-By: Jordan Harband <ljharb@gmail.com>

Author: aduh95

test/fixtures/process/different-registry-per-thread.mjs

@@ -1,15 +1,26 @@
 import { isMainThread, Worker } from 'node:worker_threads';
 
+const registeredRefs = [];
+
+const ref = { foo: 'foo' };
+registeredRefs.push(ref);
+
 if (isMainThread) {
-  process.finalization.register({ foo: 'foo' }, () => {
+  process.finalization.register(ref, () => {
     process.stdout.write('shutdown on main thread\n');
   });
 
   const worker = new Worker(import.meta.filename);
 
+  worker.on('error', (err) => {
+    // Referencing `registeredRefs` here to avoid `ref` being GCed before the worker exits.
+    console.log(registeredRefs);
+    throw err;
+  });
+
   worker.postMessage('ping');
 } else {
-  process.finalization.register({ foo: 'bar' }, () => {
+  process.finalization.register(ref, () => {
     process.stdout.write('shutdown on worker\n');
   });
 }

test/parallel/test-memory-usage.js

@@ -44,6 +44,8 @@ if (r.arrayBuffers > 0) {
   const after = process.memoryUsage();
   assert.ok(after.external - r.external >= size,
             `${after.external} - ${r.external} >= ${size}`);
-  assert.strictEqual(after.arrayBuffers - r.arrayBuffers, size,
-                     `${after.arrayBuffers} - ${r.arrayBuffers} === ${size}`);
+  // `arrayBuffers` is process-wide, so unrelated backing stores may be freed
+  // between the two snapshots. Check that the live ArrayBuffer is included.
+  assert.ok(after.arrayBuffers >= size,
+            `${after.arrayBuffers} >= ${size}`);
 }