Worker Threads flag (node v10.5+)

[alexcastillo]

Hi,

Thanks for all the work you've done with ts-node!

I'm currently trying to pass the --experimental-worker flag for Worker Threads support but it doesn't seem to be respecting the flag.

I've tried:

• ts-node ./file.ts --experimental-worker
• node --experimental-worker --require ts-node/register ./file.ts

And I get the following error:

• error TS2307: Cannot find module 'worker_threads'.

Any ideas?

[blakeembrey]

It’s not defined in the TypeScript definition for node.js yet.

[alexcastillo]

Thanks for replying. Any chance you can give me more context on this?

Any ideas on where these definitions are located in the TypeScript project?

[blakeembrey]

When you installed @types/node - https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/node/index.d.ts

[alexcastillo]

Thanks, @blakeembrey!

[jmgomez]

Any idea of when they are going to be defined?

[blakeembrey]

I don’t. You would have to add them yourself if you want them ASAP. It’s a community project to type third-party libraries.

[linusnorton]

They're not usable via ts-node at the moment anyway. You get an error from node:

TypeError [ERR_WORKER_UNSUPPORTED_EXTENSION]: The worker script extension must be ".js" or ".mjs". Received ".ts"

[protectedvar]

define NODE_OPTIONS as enviroment variable

`export NODE_OPTIONS=--experimental-worker

ts-node ./file.ts`

[maciejmatu]

If somebody wants to write thread workers as .ts files, it's possible by having an intermediate .js file that only acts as the importer. It also requires option allowJs: true in tsconfig.json

worker.import.js

require('ts-node').register();
require(path.resolve(__dirname, 'worker.ts'));

worker.ts

// regular ts file 

[marcpearson]

@maciejmatu HI, i tried what you said in your comment for using ts-node with worker_threads but my node/ts-node app crash with this:

/vagrant/node_modules/rxjs/internal/util/hostReportError.js:4
setTimeout(function () { throw err; });

Exit code of the worker is 1

AllowJs is true in my tsconfig.json

My backend start command is:
node -r ts-node/register src/index.ts
Running : node 10.15.3 with experimental worker, ts-node 7.0.1

[maciejmatu]

@marcpearson not sure what exactly might be the issue in your build, but to expand on what I wrote previosuly:

I run the app using ts-node src/index.ts and in index.ts I initialize worker

const workerFile = process.env.NODE_ENV === 'production'
  ? 'worker.js'
  : 'worker.import.js';

  new Worker(path.resolve(__dirname, workerFile), { workerData });

In production the app will be compiled to js, so I just import worker.js file that will be there. In development on the other hand I need an intermediate file, that has .js file extension and just imports worker.ts

worker.import.js file

const path = require('path');

require('ts-node').register();
require(path.resolve(__dirname, './worker.ts'));

And the last file is worker.ts itself, where you have the worker logic.

[drachehavoc]

I made a different solution with a dynamic approach, I create an a function with a eval worker whos import the TS file.

check the code below:

import {
    Worker,
    isMainThread,
    parentPort,
    workerData,
    WorkerOptions
} from "worker_threads";

//
// WORKAROUND (GAMBIARRA)
//
const workerTs = (file: string, wkOpts: WorkerOptions) => {
    wkOpts.eval = true;
    if (!wkOpts.workerData) {
        wkOpts.workerData = {};
    }
    wkOpts.workerData.__filename = file;
    return new Worker(`
            const wk = require('worker_threads');
            require('ts-node').register();
            let file = wk.workerData.__filename;
            delete wk.workerData.__filename;
            require(file);
        `,
        wkOpts
    );
}

//
// MAIN FUNCTION
//
const main = () => {
    setInterval(() => console.log('main'), 1000);
    let wk = workerTs(__filename, {
        workerData: [1, 2, 3, 4, 5, 6, 7, 8, 9]
    });
    wk.on("online", () => console.log('Worker UP'));
    wk.on("message", (msg) => console.log('message:', msg));
    wk.on("exit", (code) => console.warn('exit', code));
    wk.on("error", (err) => console.error('error', err));
}

//
// THREAD FUNCTION
//
const thread = () => {
    if (!parentPort) return;
    console.log(workerData)
    parentPort.postMessage('asdas')
}

//
// RUN MAIN OR THREAD
//
isMainThread ? main() : thread();

ps: sorry for the bad english.

[liswin]

This is a simple program that I am trying to run to find a factorial of a number using worker_threads and it throws me Error: Cannot find module 'worker_threads
node version: 10.5.0

index.ts

import { Worker } from 'worker_threads';
let workerData = {}
const worker = new Worker('./worker.js', { workerData } );

worker.on('message', (result:any) => {
    console.log(result);
});

worker.js

const path = require('path');
const { workerData } = require('worker_threads');
 
require('ts-node').register();
require(path.resolve(__dirname, workerData.path));`

worker.ts
`import { parentPort, workerData } from 'worker_threads';

function factorial(n: number): number {
    if (n === 1 || n === 0) {
        return 1;
    }
    return factorial(n - 1) * n;
}
if (parentPort) {
    parentPort.postMessage(
        factorial(workerData.value)
    );
}

I tried running index.ts with the command ts-node index.ts --experimental-worker, it throws me

Error: Cannot find module 'worker_threads'
tsconfig.js
{ "compilerOptions": { "target": "es5", "module": "commonjs", "allowJs": true, } }
May I know if I am missing something here ? @maciejmatu

[harrysolovay]

Why was this thread closed? Seems like it's still an issue.

[cspotcode]

@harrysolovay

It was closed because the error reported in this issue, error TS2307: Cannot find module 'worker_threads'., is caused by the reason explained in this comment: #676 (comment)

It’s not defined in the TypeScript definition for node.js yet.

This means that ts-node is behaving as intended, and the error is being correctly reported, as designed.

Is there any other information that might indicate that this problem is a ts-node issue, rather than an issue with @types/node?

[codeonmoon]

@maciejmatu HI, i tried what you said in your comment for using ts-node with worker_threads but my node/ts-node app crash with this:

/vagrant/node_modules/rxjs/internal/util/hostReportError.js:4 setTimeout(function () { throw err; });

Exit code of the worker is 1

AllowJs is true in my tsconfig.json

My backend start command is: node -r ts-node/register src/index.ts Running : node 10.15.3 with experimental worker, ts-node 7.0.1

@marcpearson - Is this issue resolved in your case?