some code example outdated in the doc for worker_threads

[skyitachi]

• Version: 10.5.0
• Platform: Darwin
• Subsystem:

I found in the docs for the Worker following code example is outdated

const assert = require('assert');
const {
  Worker, MessageChannel, MessagePort, isMainThread
} = require('worker_threads');
if (isMainThread) {
  const worker = new Worker(__filename);
  const subChannel = new MessageChannel();
  worker.postMessage({ hereIsYourPort: subChannel.port1 }, [subChannel.port1]);
  subChannel.port2.on('message', (value) => {
    console.log('received:', value);
  });
} else {
  require('worker_threads').once('workerMessage', (value) => {
    assert(value.hereIsYourPort instanceof MessagePort);
    value.hereIsYourPort.postMessage('the worker is sending this');
    value.hereIsYourPort.close();
  });
}

should use parentPort.on("message") replaced

[vsemozhetbyt]

I am a bit confused. There is no .once('workerMessage' in the linked doc.

[mullim]

This is brand new and experimental (link to docs). It is not outdated and was introduced in Node 10.5.0

[skyitachi]

@vsemozhetbyt please checkout the url
@mulligan121 thanks, but the code

const assert = require('assert');
const {
  Worker, MessageChannel, MessagePort, isMainThread
} = require('worker_threads');
if (isMainThread) {
  const worker = new Worker(__filename);
  const subChannel = new MessageChannel();
  worker.postMessage({ hereIsYourPort: subChannel.port1 }, [subChannel.port1]);
  subChannel.port2.on('message', (value) => {
    console.log('received:', value);
  });
} else {
  require('worker_threads').once('message', (value) => {
    assert(value.hereIsYourPort instanceof MessagePort);
    value.hereIsYourPort.postMessage('the worker is sending this');
    value.hereIsYourPort.close();
  });
}

still cannot run on 10.6.0, you can make a try, the following is my running result

node --experimental-worker worker.js

events.js:167
      throw er; // Unhandled 'error' event
      ^
TypeError: require(...).once is not a function
    at Object.<anonymous> (/Users/skyitachi/tmp/node/worker.js:13:29)
    at Module._compile (internal/modules/cjs/loader.js:689:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10)
    at Module.load (internal/modules/cjs/loader.js:599:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:538:12)
    at Function.Module._load (internal/modules/cjs/loader.js:530:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:742:12)
    at MessagePort.port.on (internal/worker.js:425:27)
    at MessagePort.emit (events.js:182:13)
    at MessagePort.onmessage (internal/worker.js:66:8)
Emitted 'error' event at:
    at Worker.[kOnErrorMessage] (internal/worker.js:296:10)
    at Worker.[kOnMessage] (internal/worker.js:306:37)
    at MessagePort.Worker.(anonymous function).on (internal/worker.js:243:57)
    at MessagePort.emit (events.js:182:13)
    at MessagePort.onmessage (internal/worker.js:66:8)

[devsnek]

it should be parentPort.once not require('worker_threads')

[vsemozhetbyt]

There seems to be a fixing PR: #21486

[skyitachi]

@vsemozhetbyt thanks

[x-077]

You are missing the ParentPort in the import.