Version

v20.12.0

Platform

Darwin toyobayashiM2Pro.local 23.4.0 Darwin Kernel Version 23.4.0: Fri Mar 15 00:12:49 PDT 2024; root:xnu-10063.101.17~1/RELEASE_ARM64_T6020 arm64

Subsystem

worker_threads

What steps will reproduce the bug?

1. Create index.js

   process.once('beforeExit', () => {
     console.log('beforeExit')
   })
   
   const { Worker } = require('worker_threads')
   
   const w = new Worker(`
   const { parentPort } = require('worker_threads');
   parentPort.on('message', (msg) => {
     parentPort.postMessage(msg);
   });
   `, { eval: true })
   
   // w.on('message', () => {}) // <--- enable this line to let Node.js exit
   
   w.unref()
   
   w.on('message', () => {}) // <--- or comment this line to let Node.js exit

2. Run node ./index.js

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

Always

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

worker.unref() make Node.js exit no matter where worker.on('message', () => {}) appear.

What do you see instead?

Node.js process stuck forever.

Additional information

w.on('message', () => {})
w.unref()
w.on('message', () => {})
// ✅ exit

w.unref()
w.on('message', () => {})
// ❗️ stuck

w.on('message', () => {})
w.unref()
// ✅ exit

w.unref()
// ✅ exit

Not sure if this is expected behavior.