How to add backpressure to Socket.IO in production

Real-time applications often start with a simple promise: push data from the server to the client as it happens. You install Socket.IO, set up a namespace, and start calling socket.emit() . It works perfectly in development and even in early production with a few dozen clients. But as you scale to hundreds or thousands of concurrent users, things start to break in ways that aren't immediately obvious. You might notice your Node.js process memory usage slowly climbing. Then it spikes. Eventually,