Built a Layer-7 HTTP load balancer in Go with round-robin routing, active health checks, retry handling, and backend failover support. Implemented worker-pool based concurrency control, graceful shutdown, and hot backend reloads without dropping in-flight requests. Stress-tested the system with 8.2M+ requests using k6 under burst traffic and backend failure scenarios, investigating bottlenecks related to connection reuse, port exhaustion, and throughput stability.