Added example of clustering. [Closes #8]

README.md

@@ -434,6 +434,67 @@ Ultimately if enough people want a Redis driver instead of Mongo, I will write
 one. (Please open an issue requesting it). For now, Agenda decided to focus on
 guaranteed persistence.
 
+### Spawning / forking processes.
+
+Ultimately Agenda can work from a single job queue across multiple machines, node processes, or forks. If you are interested in having more than one worker, @Bars3s has written up a fantastic example of how one might do it:
+
+```js
+var cluster = require('cluster'),
+    cpuCount = require('os').cpus().length,
+    jobWorkers = [],
+    webWorkers = [];
+
+if (cluster.isMaster) {
+
+    // Create a worker for each CPU
+    for (var i = 0; i < cpuCount; i += 1) {
+        addJobWorker();
+        addWebWorker();
+    }
+
+    cluster.on('exit', function (worker, code, signal) {
+
+        if (jobWorkers.indexOf(worker.id) != -1) {
+            console.log('job worker ' + worker.process.pid + ' died. Trying to respawn...');
+            removeJobWorker(worker.id);
+            addJobWorker();
+        }
+
+        if (webWorkers.indexOf(worker.id) != -1) {
+            console.log('http worker ' + worker.process.pid + ' died. Trying to respawn...');
+            removeWebWorker(worker.id);
+            addWebWorker();
+        }
+    });
+
+} else {
+    if (process.env.web) {
+        console.log('start http server: ' + cluster.worker.id);
+        require('./app/web-http');//initialize the http server here
+    }
+
+    if (process.env.job) {
+        console.log('start job server: ' + cluster.worker.id);
+        require('./app/job-worker');//initialize the agenda here 
+    }
+}
+
+function addWebWorker() {
+    webWorkers.push(cluster.fork({web: 1}).id);
+}
+
+function addJobWorker() {
+    webWorkers.push(cluster.fork({job: 1}).id);
+}
+
+function removeWebWorker(id) {
+    webWorkers.splice(webWorkers.indexOf(id), 1);
+}
+
+function removeJobWorker(id) {
+    jobWorkers.splice(jobWorkers.indexOf(id), 1);
+}
+```