Can Web Workers utilize 100% of a multi-core CPU?

Question

I've been trying to find out just how capable web workers are of distributing processor load. I've yet to find any demos that seem to be able to get my quad core 2600k to even 50%, let alone 100%.

Here's a web worker demo I've tried to max my CPU on:

http://nerget.com/rayjs-mt/rayjs.html

(If you go into the page's HTML with firebug /chrome-inspect-element and make the canvas larger, you can make it raytrace a much larger image - I set mine to 1920 x 1080)

Even with 4, 8, 16 workers selected, I can't get my CPU utilization above around 25% per core.

Does anyone know if you can utilize 100% of the CPU through web workers?

(I'm using Google Chrome.)

Answer 1

This uses 100% on my 2500K:

var code = "while(true){}";
var URL = window.webkitURL || window.URL;
var bb = new Blob([code], {type : 'text/javascript'});

code = URL.createObjectURL(bb);

new Worker(code);
new Worker(code);
new Worker(code);
new Worker(code);

http://jsfiddle.net/MTJ27/81/

Answer 2

I have re-written Esailija's answer using the new blob constructor. BlobBuilder is now outdated, so you must use Blob() instead, see here for the deets: http://updates.html5rocks.com/2012/06/Don-t-Build-Blobs-Construct-Them

window.URL = window.URL || window.webkitURL;

var blob = new Blob(["while(true){}"], {type: 'text/javascript'});

code = window.URL.createObjectURL(blob);

new Worker(code);
new Worker(code);
new Worker(code);
new Worker(code);

http://jsfiddle.net/MTJ27/15/