stderr piping repro case

README.md

in one terminal window, run node parent.js in another, run tail -f test.log

with the cp.stderr.destroy line commented out, the node parent.js process will not automatically exit. With the cp.stderr.destroy line uncommented, the parent process correctly exits and the child process is unaffected.

parent.js

const child_process = require('child_process');

const cp = child_process.spawn('node', ['test.js'], {
  detached: true,
  stdio: ['ignore', 'ignore', 'pipe', 'ipc']
});

console.log(`Child pid: ${cp.pid}`);

let buffer = '';
const handler = data => buffer += data.toString('utf8');

cp.stderr.on('data', handler);

cp.on('message', (msg) => {
  console.log(buffer);

  if (msg.started) {
    cp.stderr.off('data', handler);
    // leave this line commented out and the parent won't exit
    // cp.stderr.destroy();

    cp.disconnect();
    cp.unref();
  }
})

test.js

const fs = require('fs');

let count = 0;

const ws = fs.createWriteStream('test.log');

setInterval(() => {
  if (count === 10) {
    if (process.send) {
      process.send({ started: true });
    }
  }

  console.error(`count: ${count}`);
  ws.write(`count: ${count}\n`);
  count++;
}, 1000);