process: fix finalization cleanup ref tracking

Use SafeSet collections for finalization refs so insertion, removal,
and emptiness checks match the identity-based tracking model.
This also fixes cleanup removal for collected refs. Previously cleanup
used the ref index as the splice delete count, which could remove later
live refs when the collected ref was not first.
Signed-off-by: Kamat, Trivikram <16024985+trivikr@users.noreply.github.com>
Assisted-by: openai:gpt-5.5
PR-URL: #64087Fixes: #64086
Reviewed-By: René <contact.9a5d6388@renegade334.me.uk>

Author: trivikr

lib/internal/process/finalization.js

@@ -2,11 +2,8 @@
 // This file is a modified version of the on-exit-leak-free module on npm.
 
 const{
- ArrayPrototypeFilter,
- ArrayPrototypeIndexOf,
- ArrayPrototypePush,
- ArrayPrototypeSplice,
  SafeFinalizationRegistry,
+ SafeSet,
  SafeWeakRef,
 }=primordials;
 const{ validateObject, kValidateObjectAllowFunction }=require('internal/validators');
@@ -20,8 +17,8 @@ function createFinalization() {
 
 constrefs={
 __proto__: null,
-exit: [],
-beforeExit: [],
+exit: newSafeSet(),
+beforeExit: newSafeSet(),
 };
 
 constfunctions={
@@ -31,21 +28,21 @@ function createFinalization() {
 };
 
 functioninstall(event){
-if(refs[event].length>0){
+if(refs[event].size>0){
 return;
 }
 
 process.on(event,functions[event]);
 }
 
 functionuninstall(event){
-if(refs[event].length>0){
+if(refs[event].size>0){
 return;
 }
 
 process.removeListener(event,functions[event]);
 
-if(refs.exit.length===0&&refs.beforeExit.length===0){
+if(refs.exit.size===0&&refs.beforeExit.size===0){
 registry=null;
 }
 }
@@ -70,14 +67,14 @@ function createFinalization() {
 fn(obj,event);
 }
 }
-refs[event]=[];
+refs[event].clear();
 }
 
 functionclear(ref){
 for(consteventof['exit','beforeExit']){
-constindex=ArrayPrototypeIndexOf(refs[event],ref);
-ArrayPrototypeSplice(refs[event],index,index+1);
-uninstall(event);
+if(refs[event].delete(ref)){
+uninstall(event);
+}
 }
 }
 
@@ -90,7 +87,7 @@ function createFinalization() {
 registry||=newSafeFinalizationRegistry(clear);
 registry.register(obj,ref);
 
-ArrayPrototypePush(refs[event],ref);
+refs[event].add(ref);
 }
 
 /**
@@ -130,10 +127,12 @@ function createFinalization() {
 }
 registry.unregister(obj);
 for(consteventof['exit','beforeExit']){
-refs[event]=ArrayPrototypeFilter(refs[event],(ref)=>{
+for(constrefofrefs[event]){
 const_obj=ref.deref();
-return_obj&&_obj!==obj;
-});
+if(!_obj||_obj===obj){
+refs[event].delete(ref);
+}
+}
 uninstall(event);
 }
 }

test/fixtures/process/finalization-cleanup.mjs

@@ -0,0 +1,34 @@
+import{deepStrictEqual}from'assert'
+import{setImmediate}from'timers/promises'
+
+constkeptAlive=[]
+constfinalized=[]
+
+functiononFinalize(obj){
+finalized.push(obj.name)
+}
+
+{
+constfirst={name: 'first'}
+letcollected={name: 'collected'}
+constthird={name: 'third'}
+
+keptAlive.push(first,third)
+
+process.finalization.register(first,onFinalize)
+process.finalization.register(collected,onFinalize)
+process.finalization.register(third,onFinalize)
+
+collected=null
+}
+
+// Give V8 a few chances to collect `collected` and run the
+// FinalizationRegistry cleanup before process exit.
+for(leti=0;i<10;i++){
+gc()
+awaitsetImmediate()
+}
+
+process.on('exit',function(){
+deepStrictEqual(finalized,['first','third'])
+})

test/parallel/test-process-finalization.mjs

@@ -9,6 +9,7 @@ import assert from 'assert';
 constfiles=[
 'close.mjs',
 'before-exit.mjs',
+'finalization-cleanup.mjs',
 'gc-not-close.mjs',
 'unregister.mjs',
 'different-registry-per-thread.mjs',