fix: fix wrong stream canceled up after cloning (v6) (#4414)

snyamathi · web-flow · commit 44c23e5e166a · 2025-08-18T09:59:56.000+02:00
* Add failing test repro

* fix: register correct stream with finalization registry

* fix: node21

* port changes

* remove duplicate test

* be defensive with finalization registry
diff --git a/lib/web/fetch/body.js b/lib/web/fetch/body.js
@@ -296,10 +296,6 @@ function cloneBody (instance, body) {
   // 1. Let « out1, out2 » be the result of teeing body’s stream.
   const [out1, out2] = body.stream.tee()
 
-  if (hasFinalizationRegistry) {
-    streamRegistry.register(instance, new WeakRef(out1))
-  }
-
   // 2. Set body’s stream to out1.
   body.stream = out1
 
diff --git a/lib/web/fetch/response.js b/lib/web/fetch/response.js
@@ -240,6 +240,11 @@ class Response {
     // 2. Let clonedResponse be the result of cloning this’s response.
     const clonedResponse = cloneResponse(this[kState])
 
+    // Note: To re-register because of a new stream.
+    if (hasFinalizationRegistry && this[kState].body?.stream) {
+      streamRegistry.register(this, new WeakRef(this[kState].body.stream))
+    }
+
     // 3. Return the result of creating a Response object, given
     // clonedResponse, this’s headers’s guard, and this’s relevant Realm.
     return fromInnerResponse(clonedResponse, getHeadersGuard(this[kHeaders]))
diff --git a/test/fetch/fire-and-forget.js b/test/fetch/fire-and-forget.js
@@ -1,17 +1,54 @@
 'use strict'
 
 const { randomFillSync } = require('node:crypto')
-const { setTimeout: sleep } = require('timers/promises')
+const { setTimeout: sleep, setImmediate: nextTick } = require('node:timers/promises')
 const { test } = require('node:test')
-const { fetch, Agent, setGlobalDispatcher } = require('../..')
+const { fetch, Request, Response, Agent, setGlobalDispatcher } = require('../..')
 const { createServer } = require('node:http')
 const { closeServerAsPromise } = require('../utils/node-http')
 
 const blob = randomFillSync(new Uint8Array(1024 * 512))
 
+const hasGC = typeof global.gc !== 'undefined'
+
 // Enable when/if FinalizationRegistry in Node.js 18 becomes stable again
 const isNode18 = process.version.startsWith('v18')
 
+// https://github.com/nodejs/undici/issues/4150
+test('test finalizer cloned request', async () => {
+  if (!hasGC) {
+    throw new Error('gc is not available. Run with \'--expose-gc\'.')
+  }
+
+  const request = new Request('http://localhost', { method: 'POST', body: 'Hello' })
+
+  request.clone()
+
+  await nextTick()
+  // eslint-disable-next-line no-undef
+  gc()
+
+  await nextTick()
+  await request.arrayBuffer() // check consume body
+})
+
+test('test finalizer cloned response', async () => {
+  if (!hasGC) {
+    throw new Error('gc is not available. Run with \'--expose-gc\'.')
+  }
+
+  const response = new Response('Hello')
+
+  response.clone()
+
+  await nextTick()
+  // eslint-disable-next-line no-undef
+  gc()
+
+  await nextTick()
+  await response.arrayBuffer() // check consume body
+})
+
 test('does not need the body to be consumed to continue', { timeout: 180_000, skip: isNode18 }, async (t) => {
   const agent = new Agent({
     keepAliveMaxTimeout: 10,
