use FinalizationRegistry to cancel the body if response is collected

lib/web/fetch/index.js

@@ -120,12 +120,16 @@ class Fetch extends EE {
   }
 }
 
+function handleFetchDone (response) {
+  finalizeAndReportTiming(response, 'fetch')
+}
+
 // https://fetch.spec.whatwg.org/#fetch-method
 function fetch (input, init = undefined) {
   webidl.argumentLengthCheck(arguments, 1, 'globalThis.fetch')
 
   // 1. Let p be a new promise.
-  const p = createDeferredPromise()
+  let p = createDeferredPromise()
 
   // 2. Let requestObject be the result of invoking the initial value of
   // Request as constructor with input and init as arguments. If this throws
@@ -185,16 +189,17 @@ function fetch (input, init = undefined) {
       // 3. Abort controller with requestObject’s signal’s abort reason.
       controller.abort(requestObject.signal.reason)
 
+      const realResponse = responseObject?.deref()
+
       // 4. Abort the fetch() call with p, request, responseObject,
       //    and requestObject’s signal’s abort reason.
-      abortFetch(p, request, responseObject, requestObject.signal.reason)
+      abortFetch(p, request, realResponse, requestObject.signal.reason)
     }
   )
 
   // 12. Let handleFetchDone given response response be to finalize and
   // report timing with response, globalObject, and "fetch".
-  const handleFetchDone = (response) =>
-    finalizeAndReportTiming(response, 'fetch')
+  // see function handleFetchDone
 
   // 13. Set controller to the result of calling fetch given request,
   // with processResponseEndOfBody set to handleFetchDone, and processResponse
@@ -228,10 +233,11 @@ function fetch (input, init = undefined) {
 
     // 4. Set responseObject to the result of creating a Response object,
     // given response, "immutable", and relevantRealm.
-    responseObject = fromInnerResponse(response, 'immutable')
+    responseObject = new WeakRef(fromInnerResponse(response, 'immutable'))
 
     // 5. Resolve p with responseObject.
-    p.resolve(responseObject)
+    p.resolve(responseObject.deref())
+    p = null
   }
 
   controller = fetching({
@@ -314,7 +320,10 @@ const markResourceTiming = performance.markResourceTiming
 // https://fetch.spec.whatwg.org/#abort-fetch
 function abortFetch (p, request, responseObject, error) {
   // 1. Reject promise with error.
-  p.reject(error)
+  if (p) {
+    // We might have already resolved the promise at this stage
+    p.reject(error)
+  }
 
   // 2. If request’s body is not null and is readable, then cancel request’s
   // body with error.
@@ -1066,7 +1075,10 @@ function fetchFinale (fetchParams, response) {
   // 4. If fetchParams’s process response is non-null, then queue a fetch task to run fetchParams’s
   //    process response given response, with fetchParams’s task destination.
   if (fetchParams.processResponse != null) {
-    queueMicrotask(() => fetchParams.processResponse(response))
+    queueMicrotask(() => {
+      fetchParams.processResponse(response)
+      fetchParams.processResponse = null
+    })
   }
 
   // 5. Let internalResponse be response, if response is a network error; otherwise response’s internal response.

lib/web/fetch/response.js

@@ -26,9 +26,21 @@ const { URLSerializer } = require('./data-url')
 const { kHeadersList, kConstruct } = require('../../core/symbols')
 const assert = require('node:assert')
 const { types } = require('node:util')
+const { isDisturbed } = require('node:stream')
 
 const textEncoder = new TextEncoder('utf-8')
 
+const hasFinalizationRegistry = globalThis.FinalizationRegistry && process.version.indexOf('v18') !== 0
+let registry
+
+if (hasFinalizationRegistry) {
+  registry = new FinalizationRegistry((stream) => {
+    if (!stream.locked && !isDisturbed(stream)) {
+      stream.cancel('Response object has been garbage collected')
+    }
+  })
+}
+
 // https://fetch.spec.whatwg.org/#response-class
 class Response {
   // Creates network error Response.
@@ -510,6 +522,11 @@ function fromInnerResponse (innerResponse, guard) {
   response[kHeaders] = new Headers(kConstruct)
   response[kHeaders][kHeadersList] = innerResponse.headersList
   response[kHeaders][kGuard] = guard
+
+  if (hasFinalizationRegistry && innerResponse.body?.stream) {
+    registry.register(response, innerResponse.body.stream)
+  }
+
   return response
 }
 

test/fetch/fire-and-forget.js

@@ -0,0 +1,49 @@
+'use strict'
+
+const { randomFillSync } = require('node:crypto')
+const { setTimeout: sleep } = require('timers/promises')
+const { test } = require('node:test')
+const { fetch, Agent, setGlobalDispatcher } = require('../..')
+const { createServer } = require('node:http')
+const { closeServerAsPromise } = require('../utils/node-http')
+
+const blob = randomFillSync(new Uint8Array(1024 * 512))
+const fmt = new Intl.NumberFormat()
+
+test('does not need the body to be consumed to continue', async (t) => {
+  const agent = new Agent({
+    keepAliveMaxTimeout: 10,
+    keepAliveTimeoutThreshold: 10
+  })
+  setGlobalDispatcher(agent)
+  const server = createServer((req, res) => {
+    res.writeHead(200)
+    res.end(blob)
+  })
+  t.after(closeServerAsPromise(server))
+
+  await new Promise((resolve) => {
+    server.listen(0, resolve)
+  })
+
+  const url = new URL(`http://127.0.0.1:${server.address().port}`)
+
+  const batch = 50
+  const delay = 0
+  let total = 0
+  while (total < 10000) {
+    const array = new Array(batch)
+    for (let i = 0; i < batch; i++) {
+      array[i] = fetch(url).catch(() => {})
+    }
+    await Promise.all(array)
+    await sleep(delay)
+
+    console.log(
+      'RSS',
+      (process.memoryUsage.rss() / 1024 / 1024) | 0,
+      'MB after',
+      fmt.format((total += batch)) + ' fetch() requests'
+    )
+  }
+})