Parallel.js

Writer and consultant

• Microsoft C# MVP
• Active contributions to open-source projects
• Articles for CodeProject, SitePoint, tuts+, ...

Languages and technologies

• C#, JavaScript, and C/C++
• Full web stack (client and server)
• High Performance and Embedded Computing, IoT

1. Web Worker
2. Parallel.js
3. Demos, demos, demos
4. SIMD.js

• What makes JavaScript suitable for parallelism?
  • Browsing contexts
  • Implicit synchronization
  • Explicit spawning

• Communication over messages
• Direct send, indirect receive (event)
• Mediated over reactor, i.e., thread-safe
• Avoids classic race conditions
• Drawback: Messages are always strings
• Need to serialize arguments (JSON)

• Receiving from some window:

  window.addEventListener('message', function (ev) {
  	ev.source.postMessage('Howdy Cowboy!', ev.origin);
  }, false);
  					

• Sending to a created window:

  var popup = window.open(/* ... */);
  popup.postMessage('Hello World!', '*');
  					

• Dedicated workers exposed as Worker
• Shared workers via SharedWorker
• Service workers come as ServiceWorker

var fs = (function () { 
	postMessage('Hello World');
}).toString(); 
var blob = new Blob(
   [fs.substr(13, fs.length - 14)],
   { type: 'text/javascript' }
);
var url = window.URL.createObjectURL(blob);
var worker = new Worker(url);
worker.addEventListener('message', function (ev) {
	console.log(ev.data);
}, false);
			

• Elegant worker wrapper
• Easy to utilize
• Data-driven API (data first)
• Uses of Promise to avoid callback hell

• Creating a new parallel context

  var p1 = new Parallel('Hello World!');
  var p2 = new Parallel([1, 2, 3, 4, 5]);
  					

• Spawning a new worker:

  p1.spawn(data => data.split('').reverse().join(''));
  					

• Using the result:

  p2.spawn(data => data.length).then(data => console.log(data));
  					

• Helpers to avoid boilerplate
• Parallel algorithms (scatter, gather, ...)
• Everything is callback-based

• Each worker starts with a clean context
• Include external functions
• Include required libraries
• Define auxiliary methods

• Gather / scatter operations:

  var p1 = new Parallel([1, 2, 3, 4, 5]);
  p1.map(element => Math.exp(element * 0.1));
  var p2 = new Parallel(_.range(100));
  p2.reduce(elements => elements[0] + elements[1]));
  					

• Defining the environment:

  var p = new Parallel([ /* ... */ ], {
  	env: { a: 10 }, envNamespace: 'parallel'
  });
  					

• Including helpers:

  function factorial (n) { /* ... */ }
  p.require(factorial);
  					

var a = SIMD.Float32x4(1, 2, 3, 4);
var b = SIMD.Float32x4(5, 6, 7, 8);
var sum = SIMD.Float32x4.add(a, b);
var reversed = SIMD.Float32x4.swizzle(b, 3, 2, 1, 0);
var difference = SIMD.Float32x4.sub(reversed, a);
var mixed = SIMD.Float32x4.shuffle(a, b, 0, 2, 5, 7);
			

• Feel free to contact me

• Web: florian-rappl.de
• eMail: mail@florian-rappl.de
• Twitter: @FlorianRappl
• GitHub: github.com/FlorianRappl

• Find the presentation at talks.florian-rappl.de/Paralleljs.