[server] use cluster module

cluster.js

@@ -0,0 +1,34 @@
+var cluster = require('cluster');
+var numCPUs = require('os').cpus().length;
+
+if (cluster.isMaster) {
+
+    // Fork workers.
+    for (var i = 0; i < numCPUs; i++) {
+        cluster.fork();
+    }
+
+    cluster.on('fork', function(worker) {
+        console.log('--- Cluster: worker ' + worker.process.pid + ' started');
+    });
+    cluster.on('exit', function(worker, code, signal) {
+        console.log('--- Cluster: Worker ' + worker.process.pid + ' died (code: ' + code + '), restarting...');
+        cluster.fork();
+    });
+
+} else {
+
+    require('./server');
+
+    if (CONFIG.CLUSTER_WORKER_RESTART_ON_MEMORY_USED) {
+        setInterval(function() {
+
+            var mem = process.memoryUsage().rss;
+            if (mem > CONFIG.CLUSTER_WORKER_RESTART_ON_MEMORY_USED) {
+                console.log('--- Cluster: worker ' + process.pid + ' used too much memory, exiting...');
+                process.exit(1);
+            }
+
+        }, 1000);
+    }
+}

config.js

@@ -13,6 +13,8 @@
 
         CACHE_TTL_PAGE_TIMEOUT: 10 * 60,
 
+        CLUSTER_WORKER_RESTART_ON_MEMORY_USED: 300 * 1024 * 1024, // 300 MB.
+
         metaLoadingTimeout: 5 * 1000,
         USER_AGENT: "Mozilla/5.0 (compatible; Iframely/" + version + "; +http://iframely.com/)",