cluster.worker.on('message', (msg) => ...) fails to register a callback if ESM file extensions is used

Version

v20.3.1

Platform

All supported platform

Subsystem

No response

What steps will reproduce the bug?

After a migration of code to ESM by using .mjs file extensions, the poolifier project has encountered issues at running internal benchmarks code.

Test case:

• main.mjs:

import cluster from 'cluster'

cluster.setupPrimary({ exec: './worker.mjs' })

const worker = cluster.fork()

worker.on('message', message => {
  console.info('message received from worker:', message)
})

worker.on('online', () => {
  console.info('worker is online')
})

worker.on('error', (error) => {
  console.info('worker error', error)
})

worker.on('disconnect', () => {
  console.info('worker disconnected')
})

worker.on('exit', () => {
  console.info('worker exited')
})

worker.send('hello')

• worker.mjs:

import cluster from 'cluster'

cluster.worker.on('message', message => {
  console.info('echo message received from main:', message)
  cluster.worker.send(message)
})

node main.mjs is frozen.

How often does it reproduce? Is there a required condition?

100% reproducible

What is the expected behavior? Why is that the expected behavior?

No response

What do you see instead?

Callback is never called if a message is sent from the primary.

Additional information

No response

Inizia eseguendo la riproduzione fornita con main.mjs e worker.mjs usando Node v20.3.1, quindi esamina il percorso del listener dei messaggi del worker del cluster coinvolto da cluster.worker.on('message'). Il lavoro è completato quando il callback riceve il messaggio inviato da worker.send('hello') quando il worker usa l'estensione .mjs, con una copertura di regressione per questo caso.