Bun socket listener invoked twice [intermittent]

index.ts

import net from 'node:net'
import { spawn } from 'bun'

const ready = Promise.withResolvers<number>()

const server = spawn({
  cmd: ['bun', 'server.ts'],
  stdio: ['inherit', 'inherit', 'inherit'],
  serialization: 'json',
  ipc: port => ready.resolve(port),
  onExit: (_, exitCode) => {
    if (exitCode) {
      console.error(`Runtime exited with code: ${exitCode}`)
      process.exit(exitCode)
    }
  },
})

const socket = net.createConnection({ port: await ready.promise })
const req = JSON.stringify({ test: true })

const result = await new Promise((resolve, reject) => {
  socket.on('connect', () => {
    socket.write(`${req}\n`)
    socket.on('data', (data: Buffer) => {
      try {
        const msg = JSON.parse(data.toString())
        resolve(msg)
      } catch(e) {
        console.error('onData error', e)
        reject(e)
      }
    })
  })
})



console.log('result', JSON.stringify(result))
server.kill()

server.ts

import net from 'node:net'

function start() {
  const server = new net.Server(socket => {
    console.log('socket connected', socket.localPort, socket.remotePort)
    socket.on('data', async data => {
      try {
        const msg = JSON.parse(data.toString())
        socket.end(JSON.stringify({ ping: 'pong', msg }))
      } catch(e) {
        console.error('fatal error', e)
        const msg = e instanceof Error ? e.message : String(e)
        socket.end(JSON.stringify({ error: msg }))
      }
    })
  })

  server.listen(0)
  const addr = server.address()
  if (addr && typeof addr === 'object') {
    return addr
  } else {
    throw new Error('NOADDR')
  }
}

try {
  if (!process.send) {
    throw new Error('Unable to establish communication with parent')
  }
  const addr = start()
  process.send(addr.port)
} catch (e) {
  console.error(e)
  process.exit(1)
}

run this in the terminal, you should see the socket connection listener sometimes fired twice:

for i in {1..100}; do bun index.ts; done

Cannot reproduce.

@guest271314 i've updated the gist, can you try to reproduce now?

I did. Nothing changed. Except the OS froze the last time I rand the code. What is the purpose of starting and stopping 100 times?