nodejs-github-bot · Sep 28, 2026 · Sep 23, 2026 · Sep 26, 2026
diff --git a/benchmark/webstreams/writable-write.js b/benchmark/webstreams/writable-write.js
@@ -0,0 +1,31 @@
+'use strict';
+const common = require('../common.js');
+const assert = require('node:assert');
+const { WritableStream } = require('node:stream/web');
+
+const bench = common.createBenchmark(main, {
+  n: [1e5],
+  type: ['await', 'queued'],
+});
+
+async function main({ n, type }) {
+  let count = 0;
+  const ws = new WritableStream({
+    write() {
+      count++;
+    },
+  }, { highWaterMark: type === 'queued' ? n : 1 });
+  const writer = ws.getWriter();
+  bench.start();
+  if (type === 'await') {
+    for (let i = 0; i < n; i++)
+      await writer.write('a');
+  } else {
+    for (let i = 1; i < n; i++)
+      writer.write('a');
+    await writer.write('a');
+  }
+  bench.end(n);
+  await writer.close();
+  assert.strictEqual(count, n);
+}
diff --git a/lib/internal/webstreams/readablestream.js b/lib/internal/webstreams/readablestream.js
@@ -1140,7 +1140,7 @@ ObjectDefineProperties(ReadableStreamBYOBReader.prototype, {
 
 class ReadableStreamDefaultController {
   [kType] = 'ReadableStreamDefaultController';
-  [kState] = {};
+  [kState];
 
   constructor(skipThrowSymbol = undefined) {
     if (skipThrowSymbol !== kSkipThrow) {
@@ -1203,7 +1203,7 @@ ObjectDefineProperties(ReadableStreamDefaultController.prototype, {
 
 class ReadableByteStreamController {
   [kType] = 'ReadableByteStreamController';
-  [kState] = {};
+  [kState];
 
   constructor(skipThrowSymbol = undefined) {
     if (skipThrowSymbol !== kSkipThrow) {

diff --git a/lib/internal/webstreams/transformstream.js b/lib/internal/webstreams/transformstream.js
@@ -303,6 +303,7 @@ TransferredTransformStream.prototype[kDeserialize] = () => {};
 
 class TransformStreamDefaultController {
   [kType] = 'TransformStreamDefaultController';
+  [kState];
 
   constructor(skipThrowSymbol = undefined) {
     if (skipThrowSymbol !== kSkipThrow) {

diff --git a/lib/internal/webstreams/writablestream.js b/lib/internal/webstreams/writablestream.js
@@ -105,19 +105,19 @@ const kSkipThrow = Symbol('kSkipThrow');
 // Shared sentinels for the "no pending request" state records. These
 // records are only ever replaced wholesale and never mutated in place,
 // so single shared instances are safe and avoid an allocation on every
-// state reset (one per write on the hot path).
-const kNilRequest = {
-  __proto__: null,
+// state reset (one per write on the hot path). The prototype is nulled
+// after creation: a `__proto__: null` literal is created in dictionary
+// mode, and these fields are loaded several times per write.
+const kNilRequest = ObjectSetPrototypeOf({
   promise: undefined,
   resolve: undefined,
   reject: undefined,
-};
-const kNilPendingAbortRequest = {
-  __proto__: null,
+}, null);
+const kNilPendingAbortRequest = ObjectSetPrototypeOf({
   abort: kNilRequest,
   reason: undefined,
   wasAlreadyErroring: false,
-};
+}, null);
 
 let releasedError;
 
@@ -502,6 +502,7 @@ ObjectDefineProperties(WritableStreamDefaultWriter.prototype, {
 
 class WritableStreamDefaultController {
   [kType] = 'WritableStreamDefaultController';
+  [kState];
 
   constructor(skipThrowSymbol = undefined) {
     if (skipThrowSymbol !== kSkipThrow) {