Scaling Real-Time Communication with Socket.io and Redis

Building real-time features is crucial for modern applications, but scaling them efficiently can be challenging.

The Challenge

When building the messaging system for Castkro, we needed to handle thousands of concurrent connections while keeping infrastructure costs low.

Architecture

// Socket.io with Redis adapter
const io = require('socket.io')(server);
const redis = require('socket.io-redis');

io.adapter(redis({ host: 'localhost', port: 6379 }));

Key Optimizations

• Use Redis pub/sub for message broadcasting
• Implement room-based messaging to reduce unnecessary broadcasts
• Add connection pooling for database queries
• Monitor and optimize memory usage

Results

These optimizations reduced our monthly infrastructure costs while supporting growing user base.