Revert 51255

lib/internal/webstreams/readablestream.js

@@ -598,8 +598,6 @@ class ReadableStream {
 
   [kTransferList]() {
     const { port1, port2 } = new MessageChannel();
-    port1.unref();
-    port2.unref();
     this[kState].transfer.port1 = port1;
     this[kState].transfer.port2 = port2;
     return [ port2 ];

lib/internal/webstreams/transfer.js

@@ -143,8 +143,6 @@ class CrossRealmTransformReadableSource {
         error);
       port.close();
     };
-
-    port.unref();
   }
 
   start(controller) {
@@ -212,7 +210,7 @@ class CrossRealmTransformWritableSink {
         error);
       port.close();
     };
-    port.unref();
+
   }
 
   start(controller) {

lib/internal/webstreams/writablestream.js

@@ -274,8 +274,6 @@ class WritableStream {
 
   [kTransferList]() {
     const { port1, port2 } = new MessageChannel();
-    port1.unref();
-    port2.unref();
     this[kState].transfer.port1 = port1;
     this[kState].transfer.port2 = port2;
     return [ port2 ];

test/parallel/test-webstream-structured-clone-no-leftovers.mjs

@@ -0,0 +1,28 @@
+import '../common/index.mjs';
+import { test } from 'node:test';
+import assert from 'node:assert';
+
+test('do not leak promises', async () => {
+  const buf = new Uint8Array(1);
+  const readable = new ReadableStream({
+    start(controller) {
+      controller.enqueue(buf);
+      controller.close();
+    }
+  });
+
+  const [out1, out2] = readable.tee();
+  const cloned = structuredClone(out2, { transfer: [out2] });
+
+  for await (const chunk of cloned) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+
+  for await (const chunk of out2) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+
+  for await (const chunk of out1) {
+    assert.deepStrictEqual(chunk, buf);
+  }
+});

test/parallel/test-whatwg-webstreams-transfer.js

@@ -464,23 +464,12 @@ const theData = 'hello';
       tracker.verify();
     });
 
-    // We create an interval to keep the event loop alive while
-    // we wait for the stream read to complete. The reason this is needed is because there's
-    // otherwise nothing to keep the worker thread event loop alive long enough to actually
-    // complete the read from the stream. Under the covers the ReadableStream uses an
-    // unref'd MessagePort to communicate with the main thread. Because the MessagePort
-    // is unref'd, it's existence would not keep the thread alive on its own. There was previously
-    // a bug where this MessagePort was ref'd which would block the thread and main thread
-    // from terminating at all unless the stream was consumed/closed.
-    const i = setInterval(() => {}, 1000);
-
     parentPort.onmessage = tracker.calls(({ data }) => {
       assert(isReadableStream(data));
       const reader = data.getReader();
       reader.read().then(tracker.calls((result) => {
         assert(!result.done);
         assert(result.value instanceof Uint8Array);
-        clearInterval(i);
       }));
       parentPort.close();
     });