Does worker.terminate() always return code 1?

[shadowgate15]

• Node.js Version: v12.20.0
• OS: macOS
• Scope (install, code, runtime, meta, other?): runtime/code
• Module (and version) (if relevant): Worker

When worker.terminate() is called, in particular from the main thread, should it always return an exitCode of 1? Or are there situations in which it would return 0?

[RaisinTen]

Doesn't this return 0?

const { Worker, isMainThread } = require('worker_threads');

if(isMainThread) {
  const worker = new Worker(__filename);
  worker.terminate().then((exitCode) => {
    console.log(exitCode);
  });
}

[addaleax]

@RaisinTen That code is going to behave unpredictably – it can return either 1 or 0 or undefined, depending on which branch of the race condition you hit.

[RaisinTen]

@addaleax Ah, yes, worker.terminate does set the exit code to 1 unless the worker exits before terminate is called.

[shadowgate15]

What if a setInterval or setTimeout is called in the worker?

[RaisinTen]

Do you mean something like this?

test.js

const { Worker, isMainThread } = require('worker_threads');

if(isMainThread) {
  const worker = new Worker(__filename);

  worker.on('exit', (exitCode) => {
    console.log(exitCode);
  });

  setTimeout(() => {
    worker.terminate();
  }, 2000);
} else {
  setTimeout(() => {
    process.exit(2);
  }, 1000);
}

In this case, since the worker has already exited by the time terminate is called, you just see this printed in the console:

❯ time node test.js
2
node test.js  0.17s user 0.03s system 9% cpu 2.094 total

[shadowgate15]

So yes but terminate() would have been called before the worker exits.

[RaisinTen]

No, in test.js, the worker exits (after 1 second) before terminate is even called (after 2 seconds). If terminate is called before the worker has exited, the worker would have an exit code of 1.

[shadowgate15]

Alright great! That is what I needed to confirm. Thank you everyone!!!