node:child_process#spawn doesn't fire close event if app exits immediately after spawned app exits

[vjpr]

What version of Bun is running?

0.6.3

What platform is your computer?

Darwin 22.2.0 arm64 arm

What steps can reproduce the bug?

Try the example from here: https://nodejs.org/api/child_process.html#event-close

const { spawn } = require('node:child_process');
const ls = spawn('ls', ['-lh', '/usr']);

ls.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

ls.on('close', (code) => {
  console.log(`child process close all stdio with code ${code}`);
});

ls.on('exit', (code) => {
  console.log(`child process exited with code ${code}`);
}); 

---

brew install watchman

import {spawn} from 'node:child_process'
import Bun from 'bun'

export default async function index() {
  console.log('Bun Child Process')

  //const watchmanBin = Bun.which('watchman')
  const watchmanBin = '/opt/homebrew/bin/watchman'

  const args = ['version']
  const spawnOpts = {
    stdio: ['pipe', 'pipe', 'pipe'],
  }
  const child = spawn(watchmanBin, args, spawnOpts)
  child.stdout.on('data', data => {
    data = data.toString('utf8')
    console.log(data)
  })
  child.stderr.on('data', data => {
    console.log(data)
  })
  child.on('close', (code, signal) => {
    console.log('closed')
    console.log({code, signal})
  })

  return 1
}

What is the expected behavior?

Node.js

Bun Child Process
{
    "version": "2023.05.15.00"
}

closed
{ code: 0, signal: null }

What do you see instead?

Bun

Bun Child Process
{
    "version": "2023.05.15.00"
}

Additional information

This prevents fb-watchman package from working.

[vjpr]

bun/src/bun.js/child_process.exports.js

Line 1095 in 0f2a79b

(exitCode, signalCode, err) => this.#handleOnExit(exitCode, signalCode, err),

calls:

bun/src/bun.js/child_process.exports.js

Line 939 in 0f2a79b

this.emit("exit", this.exitCode, this.signalCode);

Only exit is being fired...but even that is not working.

---

I check with this underlying impl, and the issue is process.nextTick is not firing...

bun/src/bun.js/child_process.exports.js

Lines 1083 to 1102 in 0f2a79b

	this.#handle = Bun.spawn({
	cmd: spawnargs,
	stdin: bunStdio[0],
	stdout: bunStdio[1],
	stderr: bunStdio[2],
	cwd: options.cwd || undefined,
	env: env || process.env,
	onExit: (handle, exitCode, signalCode, err) => {
	this.#handle = handle;
	this.pid = this.#handle.pid;
	process.nextTick(
	(exitCode, signalCode, err) => this.#handleOnExit(exitCode, signalCode, err),
	exitCode,
	signalCode,
	err,
	);
	},
	lazy: true,
	});

[vjpr]

When I add setInterval(() => {}, 100) at the bottom of my program, it prints fine.

So the issue seems to be that the program exits before the nextTick in the onExit cb can fire.

[Hanaasagi]

The issue still persists in 1.0.1

const { spawn } = require("node:child_process");

function exitHandler(code, signal) {
  console.log(code, signal);
}

const p = spawn("ls", ["-l"]);

p.on("exit", exitHandler);
p.on("close", exitHandler);

both close and exit is not emitted.