A pool of webworkers

webworker-pool.js

// From: https://gist.github.com/605541#file_js_web_worker_pool.js
// Web Worker Pool
// size is the max number of arguments
function WorkerPool(size) {
    var workers = 0,
        jobs    = [];

    // url: the url of the worker script
    // msg: the initial message to pass to the worker
    // cb : the callback to recieve messages from postMessage.
    //      return true from cb to dismiss the worker and advance the queue.
    // ctx: the context for cb.apply
    this.queueJob = function(url, msg, cb, ctx) {
        var job = {
            "url": url,
            "msg": msg,
            "cb" : cb,
            "ctx": ctx
        };
        jobs.push(job);
        if (workers < size) nextJob();
    };
    
    function nextJob() {
        if (jobs.length) {
            (function() {
                var job    = jobs.shift(),
                    worker = new Worker(job.url);
                workers++;
                worker.addEventListener('message', function(e) {
                    if (job.cb.call(job.ctx, e.data, worker)) {
                        worker.terminate();
                        delete worker;
                        workers--;
                        nextJob();
                    };
                }, false);
                worker.postMessage(job.msg);
            })();
        }
    }
}