Node.js zero-downtime reload with cluster

cluster-reload.js

var cluster = require("cluster");

function master() {
	var worker = cluster.fork();

	process.on("SIGUSR2", function() {
		var newWorker = cluster.fork();
		newWorker.on("listening", function() {
			worker.disconnect();
			worker = newWorker;
		});
	});
}

function worker() {
	require("http").createServer(function(req, res) {
		res.end("Hello");
	}).listen();
}

if (cluster.isMaster) {
	master();
}
else {
	worker();
}

this might be an over simplification of the problem. but if it suites your use case, use it :)

Care to elaborate? Some potential issues I've thought of:

• May need application-level logic to gracefully shutdown (e.g., end long-lasting requests or client connections)
• Can't zero-downtime update the master
• This example code doesn't handle concurrent SIGUSR2 signals :)