How to create/postmessage to web workers in an array

Question

Question is simple:

Example:

For (iterate based on amount of cores){
   Let worker = workers[I]
   Worker.postmessage
}

End of example .

Disclaimer: This example only shows what is expected of the end result and is in no means in what is considered "working condition" . Also note that the method used above does not return a worker for "workers[iterator]" instead just undefined.

Objective: Create working methods:

1: make array of unknown amount of workers(based on cores).

2: once that array is built, post a message to each worker and have a returned result(other than undefined).

Note: I do have a hypothesis of why it does not work:

1: web workers are created and are only accessable through the event that created them and its only acception is the onmessage "event" handler .

in defiance of my hypothesis there is such things that would say neigh to what is written above for example , like thread.js that allows for thread pooling and other procedures.

This is the main reason of why I ask , because I do know it is possible but would like a simple answer.

Thanks for your time .

Thiago Barcala · Accepted Answer · 2018-05-05 09:19:32Z

1

Here is an example:

function createWorker (workerScript) {
    const blob = new Blob([`(${workerScript})(self)`], {type: 'application/javascript'});
    return new Worker(URL.createObjectURL(blob));
};

function workerCode (self) {
    self.onmessage = function (message) {
        postMessage(`Data from worker: ${message.data}`);
    };
};

// assuming that you will send only one message to the worker,
// and that the worker will produce only one message too.
function workerPromise (worker, message) {
    const promise = new Promise((resolve, reject) => {
        worker.onmessage = resolve;
    }).then(message => message.data);
    worker.postMessage(message);
    return promise;
}

(async () => {
    const workers = [];
    for (let i = 0; i < navigator.hardwareConcurrency; i++) {
        workers.push(createWorker(workerCode));
    }

    const results = await Promise.all(
        workers.map((w, index) => workerPromise(w, `worker ${index}`))
    );

    console.log(results);
})();

answered May 5, 2018 at 9:19

Thiago Barcala

7,4232 gold badges24 silver badges26 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

static660 Over a year ago

how would I send multiple messages? Is there a way to just use your "createWorker" function and construct an array via for loop?. I just want a way to manage inumerable workers after their creation.

static660 Over a year ago

I also have no idea how your code is even supposed to work or proof that it even does , but understand that you probably wouldnt post it if it didnt. just would like a working example to I dont think ill mark this as an answer until a working example is displayed (for me and others that view for the sake of simplicity)

Daniel Klimuntowski · Accepted Answer · 2020-05-19 16:56:09Z

0

Start with the "Examples" section under: https://developer.mozilla.org/en-US/docs/Web/API/NavigatorConcurrentHardware/hardwareConcurrency

Modified example:

// in Main thread
const numberOfCPUCores = window.navigator.hardwareConcurrency;
const workerList = [];

const cpuWorkerMessageHandler = event => {
  // process message from a worker by accessing: event.data
}

for (let i = 0; i < numberOfCPUCores; i++) {
  const newWorker = new Worker('cpuworker.js');
  newWorker.addEventListener("message", cpuWorkerMessageHandler);
  workerList.push(newWorker);
}

// then, when done with all processing, terminate all workers
workerList.forEach(w => w.terminate());

answered May 19, 2020 at 16:56

Daniel Klimuntowski

787 bronze badges

Collectives™ on Stack Overflow

How to create/postmessage to web workers in an array

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related