tiny-worker

What is tiny-worker?

The tiny-worker npm package is a lightweight implementation of Web Workers for Node.js. It allows you to run JavaScript code in parallel threads, which can help improve the performance of CPU-intensive operations by offloading them to separate worker threads.

What are tiny-worker's main functionalities?

Creating a Worker

This feature allows you to create a new worker thread. The worker can execute code independently of the main thread and communicate back using messages.

const Worker = require('tiny-worker');
const worker = new Worker(function() {
  postMessage('Hello from the worker!');
});
worker.onmessage = function(event) {
  console.log(event.data); // 'Hello from the worker!'
};

Sending Messages to Worker

This feature allows the main thread to send messages to the worker thread. The worker can then process the message and send a response back to the main thread.

const Worker = require('tiny-worker');
const worker = new Worker(function() {
  onmessage = function(event) {
    postMessage('Received: ' + event.data);
  };
});
worker.onmessage = function(event) {
  console.log(event.data); // 'Received: Hello'
};
worker.postMessage('Hello');

Handling Errors in Worker

This feature allows you to handle errors that occur within the worker thread. You can set an error handler to catch and process any errors that are thrown in the worker.

const Worker = require('tiny-worker');
const worker = new Worker(function() {
  throw new Error('Something went wrong');
});
worker.onerror = function(error) {
  console.error('Worker error:', error.message); // 'Worker error: Something went wrong'
};

Other packages similar to tiny-worker

threads

The threads package is another library for managing worker threads in Node.js. It provides a higher-level API compared to worker_threads and includes features like thread pools and TypeScript support. It is more feature-rich but also more complex than tiny-worker.

node-worker-threads-pool

The node-worker-threads-pool package is a library that builds on top of the worker_threads module to provide a pool of worker threads. This can be useful for managing multiple worker threads efficiently. It offers more advanced thread management capabilities compared to tiny-worker.

README

tiny-worker

Tiny WebWorker for Server

require() is available for flexible inline Worker scripts. Optional parameters args Array & options Object; see child_process.fork() documentation.

Example

Creating a Worker from a file

The worker script:

onmessage = function (ev) {
	postMessage(ev.data);
};

The core script:

var Worker = require("tiny-worker");
var worker = new Worker("repeat.js");

worker.onmessage = function (ev) {
	console.log(ev.data);
	worker.terminate();
};

worker.postMessage("Hello World!");

Enable ES6 import/export within Worker file

The worker helper script (helper.js):

export const dataFormatter = (data) => {
	return `${data} World!`;
};

The worker script (repeat.js):

import { dataFormatter } from "./helper";

onmessage = function (ev) {
	const data = dataFormatter(ev.data);
	postMessage(data);
};

The core script:

var Worker = require("tiny-worker");
var worker = new Worker("repeat.js", [], {esm: true});

worker.onmessage = function (ev) {
	console.log(ev.data);
	worker.terminate();
};

worker.postMessage("Hello");

Creating a Worker from a Function

var Worker = require("tiny-worker");
var worker = new Worker(function () {
	self.onmessage = function (ev) {
		postMessage(ev.data);
	};
});

worker.onmessage = function (ev) {
	console.log(ev.data);
	worker.terminate();
};

worker.postMessage("Hello World!");

Debugging

To be able to debug a child process, it must have a differnt debug port than the parent. Tiny worker does this by adding a random port within a range to the parents debug port. The default Range is [1, 300], it can be changed with the setRange(min, max) method. To disable any automatic port redirection set options.noDebugRedirection = true.

automatic redirection

//parent is started with '--debug=1234'
var Worker = require("tiny-worker");
Worker.setRange(2, 20);

var worker = new Worker(function () {
	postMessage(process.debugPort); 
});

worker.onmessage = function (ev) {
	console.log(ev.data); //prints any number between 1236 and 1254
	worker.terminate();
}

manual redirection

//parent is started with '--debug=1234'
var Worker = require("tiny-worker");

var worker = new Worker(function () {
	postMessage(process.debugPort); 
}, [], {noDebugRedirection: true, execArgv: ["--debug=1235"]});

worker.onmessage = function (ev) {
	console.log(ev.data); //prints 1235
	worker.terminate();
}

Properties

onmessage

Message handler, accepts an Event

onerror

Error handler, accepts an Event

API

addEventListener(event, fn)

Adds an event listener

postMessage()

Broadcasts a message to the Worker

terminate()

Terminates the Worker

static setRange(min, max)

Sets range for debug ports, only affects current process. Returns true if successful.

FAQ

1. I have an orphaned child process that lives on past the parent process' lifespan

• Most likely a SIGTERM or SIGINT is not reaching the child process

1. How do I insure all process are terminated?

• In your core script register a listener for SIGTERM or SIGINT via process.on() which terminates (all) worker process(es) and then gracefully shutdowns via process.exit(0);

1. Why SIGTERM or SIGINT?

• Unix/BSD will work with SIGTERM, but if you also need to support Windows use SIGINT

License

Copyright (c) 2019 Jason Mulligan Licensed under the BSD-3 license