As a best-selling author, I invite you to explore my books on Amazon . Don't forget to follow me on Medium and show your support. Thank you! Your support means the world! I remember the first time I tried to build a real-time notification system for a trading application. The team needed something that could handle millions of events per second, survive server crashes, and let consumers pick up exactly where they left off after a restart. We looked at Kafka, RabbitMQ, NATS – all great tools, but heavy. They needed clusters, Zookeeper, configuration files that could fill a small novel. I wanted something simpler, something I could embed in a single Go binary and still get high throughput and durability. So I built a lightweight pub/sub broker from scratch. This article walks through that design. Every line of code here comes from a real system that served production traffic for years.…