don't check AbortSignal maxListeners on some node versions (#4045)

Author: KhafraDev

lib/web/fetch/request.js

@@ -37,6 +37,14 @@ const requestFinalizer = new FinalizationRegistry(({ signal, abort }) => {
 
 const dependentControllerMap = new WeakMap()
 
+let abortSignalHasEventHandlerLeakWarning
+
+try {
+  abortSignalHasEventHandlerLeakWarning = getMaxListeners(new AbortController().signal) > 0
+} catch {
+  abortSignalHasEventHandlerLeakWarning = false
+}
+
 function buildAbort (acRef) {
   return abort
 
@@ -424,15 +432,10 @@ class Request {
         const acRef = new WeakRef(ac)
         const abort = buildAbort(acRef)
 
-        // Third-party AbortControllers may not work with these.
-        // See, https://github.com/nodejs/undici/pull/1910#issuecomment-1464495619.
-        try {
-          // If the max amount of listeners is equal to the default, increase it
-          // This is only available in node >= v19.9.0
-          if (typeof getMaxListeners === 'function' && getMaxListeners(signal) === defaultMaxListeners) {
-            setMaxListeners(1500, signal)
-          }
-        } catch {}
+        // If the max amount of listeners is equal to the default, increase it
+        if (abortSignalHasEventHandlerLeakWarning && getMaxListeners(signal) === defaultMaxListeners) {
+          setMaxListeners(1500, signal)
+        }
 
         util.addAbortListener(signal, abort)
         // The third argument must be a registry key to be unregistered.

test/fetch/long-lived-abort-controller.js

@@ -2,7 +2,7 @@
 
 const http = require('node:http')
 const { fetch } = require('../../')
-const { once } = require('events')
+const { once, setMaxListeners } = require('node:events')
 const { test } = require('node:test')
 const { closeServerAsPromise } = require('../utils/node-http')
 const { strictEqual } = require('node:assert')
@@ -30,6 +30,7 @@ test('long-lived-abort-controller', { skip: true }, async (t) => {
   })
 
   const controller = new AbortController()
+  setMaxListeners(1500, controller.signal)
 
   // The maxListener is set to 1500 in request.js.
   // we set it to 2000 to make sure that we are not leaking event listeners.