child_process: 'close' not emitted after .disconnect() in parent process

Description

// parent.js
const child_process = require('child_process');

const child = child_process.fork('./child.js', {
    stdio: ['pipe', 'pipe', 'pipe', 'ipc']
});

setTimeout(() => {
    child.disconnect();
}, 1000);

child.on('exit', () => {
    console.log('exit');
});

child.on('close', () => {
    console.log('close');
});

child.stderr.pipe(process.stderr);
child.stdout.pipe(process.stdout);

// child.js
process.on('disconnect', () => {
    console.log('cya');
});

cya
exit

cya
exit
close

Contributor guide

Tech stack

nodejs

Domain

backend

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

basic Node.js knowledgeunderstanding of child process module

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

30

Research direction

Investigate the child process module in Node.js, specifically the handling of IPC disconnect in the parent process. Look at files like 'lib/internal/child process.js' for the implementation of 'disconnect()' and the 'close' event emission. There is a test file 'test/parallel/test child process fork close.js' that may provide context. The issue is that when the parent calls 'child.disconnect()', the 'close' event is not emitted after 'exit', unlike when the child calls 'process.disconnect()'. The fix likely requires ensuring the 'close' event is emitted in the parent side disconnect path. Check any existing comments or PRs for further hints.