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

Comienza ejecutando la reproducción proporcionada con main.mjs y worker.mjs usando Node v20.3.1; después, inspecciona la ruta del listener de mensajes del worker del cluster implicada por cluster.worker.on('message'). Se considera completado cuando el callback recibe el mensaje enviado por worker.send('hello') cuando el worker usa la extensión .mjs, con cobertura de regresión para este caso.