webworkerpool.js

Current version: 1.0.1

webworkerpool.js is a JavaScript library that can be used to manage a pool of web workers. It requires q.js or AngularJS. If you want to use this library in an AngularJS application, a module with injectable services is provided.

Motivation

In order to use multiple threads while running JavaScript in a web browser you need to rely on web workers as the only available option. Multiple threads are useful to execute JavaScript code in parallel or to separate the main thread (responsible for the UI) from some heavy-weight calculations (e.g. encryption procedures). With this separation you can be sure that your UI behaves properly no matter what goes on in the background.

Examples

To create a WebWorkerPool a web worker url resp. path is needed (here: hello-worker.js) and the capacity of the pool (number of workers, here: 8).

Create a WebWorkerPool with q.js

Create a WebWorkerPool directly:

webWorkerPool = new WebWorkerPool(Q, 'hello-worker.js', 8);

Or create a WebWorkerPoolFactory first and then create the pool:

webWorkerPoolFactory = new WebWorkerPoolFactory(Q);
webWorkerPool = webWorkerPoolFactory.createPool('hello-worker.js', 8);

Create a WebWorkerPool with AngularJS

Declare the webWorkerPool module as a module dependency:

myApp = angular.module('myApp', ['webWorkerPool']);

Then just inject either webWorkerPoolFactory or webWorkerPool. The AngularJS $q is injected automatically and you don't have to care about it.

With AngularJS you can configure default values for the worker url and the capacity of the pool. If you inject a WebWorkerPool it will already be set up with these values. The defaults must be set on the webWorkerPoolProvider:

angular.module('webWorkerPool').config(function(webWorkerPoolProvider) {
	webWorkerPoolProvider.workerUrl('hello-worker.js');
	webWorkerPoolProvider.capacity(8);
});

Or inject webWorkerPoolFactory first and then create the pool:

webWorkerPool = webWorkerPoolFactory.createPool('hello-worker.js', 8);

Use the WebWorkerPool

The usage of a WebWorkerPool is similar to that of a worker of the Web Worker API. To send a message to the worker, there is a postMessage method. To receive an answer of the worker you have to register a callback. In constrast to the Web Worker API, postMessage returns a promise and the callback is registered by calling then on the promise. So there is no need to set an onmessage callback. This is done internally by this library.

this.webWorkerPool.postMessage("Bob").then(function(event) {
    console.log(event.data);
});

Installation

Use one of the files in the dist folder for your project. There are uncompressed and compressed versions of the files. Use webworkerpool-core.js if you want to use webworkerpool.js with q.js. If you want to use webworkerpool.js in an AngularJS application use webworkerpool-angular.js or the combinded file webworkerpool-core-angular.js.

Jasmine specs

The are some jasmine specs in the spec folder. Put the files on a webserver and invoke the index.html file. The specs should run successfully.

Build

There is a UNIX shell script in the build folder if you want to build the dist files yourself. uglifyjs is required for the JavaScript compression.