Scaling Socket.IO Applications with Redis and Clustering

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Why Scale Socket.IO?

As your user base grows, a single server may not handle all real-time connections efficiently. Scaling Socket.IO ensures high availability and performance.

Using Redis Adapter

Socket.IO can integrate with Redis to synchronize events across multiple server instances.

npm install socket.io @socket.io/redis-adapter redis

const { createServer } = require('http');
const { Server } = require('socket.io');
const { createAdapter } = require('@socket.io/redis-adapter');
const { createClient } = require('redis');

const httpServer = createServer();
const io = new Server(httpServer);

const pubClient = createClient({ host: 'localhost', port: 6379 });
const subClient = pubClient.duplicate();

io.adapter(createAdapter(pubClient, subClient));

httpServer.listen(3000);

Clustering with Node.js

Use Node.js clusters to leverage multi-core systems:

const cluster = require('cluster');
const numCPUs = require('os').cpus().length;

if (cluster.isMaster) {
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }
} else {
  // Socket.IO server code here
}

Conclusion

Combining Redis and clustering ensures your Socket.IO app scales seamlessly.