https://blog.dulanwirajith.com/articles Technical articles on backend systems, cloud architecture, distributed systems, and production engineering. en-us https://blog.dulanwirajith.com/articles/system-design/time-synchronization-auction-system https://blog.dulanwirajith.com/articles/system-design/time-synchronization-auction-system How we fixed a 54-second clock skew bug in our auction platform using NTP-inspired calibration, zero backend changes, and five lines of math. Fri, 19 Jun 2026 00:00:00 GMT system-design https://blog.dulanwirajith.com/articles/backend/nginx-segfault-production-debugging https://blog.dulanwirajith.com/articles/backend/nginx-segfault-production-debugging Health checks passed. PM2 was online. SSL was valid. Yet every request returned 500. How a crashing Nginx worker hid behind a perfectly healthy application. Wed, 10 Jun 2026 00:00:00 GMT backend https://blog.dulanwirajith.com/articles/modernization/bidding-engine-tradeoffs-lessons https://blog.dulanwirajith.com/articles/modernization/bidding-engine-tradeoffs-lessons Why Redis and not Kafka? Why Fargate and not Kubernetes? And what happened in staging that nearly derailed the entire migration? The honest debrief, tradeoffs, the mistake that almost broke production, and the final results. Wed, 27 May 2026 00:00:00 GMT modernization https://blog.dulanwirajith.com/articles/aws/aws-cost-optimization-australia https://blog.dulanwirajith.com/articles/aws/aws-cost-optimization-australia Most Australian companies waste 30% on AWS. Learn real cost-cutting strategies from Sydney startups. Complete guide with code and metrics. Thu, 21 May 2026 00:00:00 GMT aws https://blog.dulanwirajith.com/articles/modernization/bidding-engine-resilience https://blog.dulanwirajith.com/articles/modernization/bidding-engine-resilience Building a reliable system means planning for failure, not just success. Here's how we engineered Multi-AZ failover, sub-30-second crash recovery, and observability that turned hour-long incidents into 10-minute fixes. Wed, 20 May 2026 00:00:00 GMT modernization https://blog.dulanwirajith.com/articles/modernization/redis-socketio-scaling https://blog.dulanwirajith.com/articles/modernization/redis-socketio-scaling The core challenge of scaling Socket.IO is that each server instance is an isolated island. Here's how we used @socket.io/redis-adapter and the Socket.IO v4 upgrade to bridge those islands into one unified real-time system. Wed, 13 May 2026 00:00:00 GMT modernization https://blog.dulanwirajith.com/articles/system-design/system-design-tradeoffs https://blog.dulanwirajith.com/articles/system-design/system-design-tradeoffs The real-world engineering decisions behind scalable systems-consistency vs availability, monolith vs microservices, sync vs async. Thu, 07 May 2026 00:00:00 GMT system-design https://blog.dulanwirajith.com/articles/modernization/bidding-engine-architecture https://blog.dulanwirajith.com/articles/modernization/bidding-engine-architecture After the production outage, we had a clear mandate: no more single points of failure. Here's the new distributed architecture we designed, from ALB through ECS Fargate to Redis, and why we made each choice. Wed, 06 May 2026 00:00:00 GMT modernization https://blog.dulanwirajith.com/articles/aws/aws-cost-optimization https://blog.dulanwirajith.com/articles/aws/aws-cost-optimization Real-world cloud cost optimization strategies applied to a production AWS environment-without sacrificing performance or reliability. Wed, 06 May 2026 00:00:00 GMT aws https://blog.dulanwirajith.com/articles/backend/scaling-backends https://blog.dulanwirajith.com/articles/backend/scaling-backends How production systems handle 100K+ concurrent users without degrading latency or reliability. Tue, 05 May 2026 00:00:00 GMT backend https://blog.dulanwirajith.com/articles/modernization/bidding-engine-incident https://blog.dulanwirajith.com/articles/modernization/bidding-engine-incident A traffic spike brought down our entire real-time platform without warning. Here's the story of what broke, why it broke, and the architectural decisions that followed. Wed, 29 Apr 2026 00:00:00 GMT modernization