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: ```javascript onmessage = function (ev) {

postMessage(ev.data);

}; ``` The core script: ```javascript 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): ```javascript export const dataFormatter = (data) => {

return `${data} World!`;

}; ``` The worker script (repeat.js): ```javascript import { dataFormatter } from "./helper"; onmessage = function (ev) {

const data = dataFormatter(ev.data);

postMessage(data);

}; ``` The core script: ```javascript 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

```javascript 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!"); ``` 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

```javascript //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

```javascript //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