Optimizing Node.js for High-Density WebSockets

Scale WebSockets using a Redis Pub/Sub backplane, optimize Linux kernel parameters (file descriptors), and use uWebSockets.js for higher throughput than ws or Socket.io.

Scaling WebSockets is hard because connections are stateful. To scale horizontally, you need a way to 'broadcast' to users on different servers (Redis Pub/Sub). Additionally, the default Linux limit of 1024 open files must be increased (ulimit -n). Senior engineers should also look at memory-per-connection; standard ws might use 30KB/socket, whereas uWebSockets.js can handle 100k+ connections with much lower overhead.