You Built a GenServer. Now Make It Fast, Observable, and Bulletproof.

Introduction

Co-authored with Sofiia Yurkevska | Originally published on Freshcode

Summary

This advanced guide bridges the gap between building GenServers and running them successfully in production environments. Building on fundamental GenServer testing principles, this article provides a comprehensive toolkit for performance optimization, observability implementation, and resilience patterns that transform weekend prototypes into production-ready systems.

Key Ideas:

• BEAM Cost Model: Understanding mailbox size, scheduler reductions, and process migrations to identify performance bottlenecks before they impact production
• Performance Patterns: Non-blocking callbacks using Task patterns, post-init heavy work with handle_continue, and strategic state externalization to ETS/persistent_term for read-heavy workloads
• Concurrency & Back-pressure: Batching and coalescing strategies, bounded mailbox patterns, and when to graduate to GenStage/Broadway for standardized pull-based back-pressure
• Observability Framework: Telemetry instrumentation, SLO-based alerting on 95th percentiles, and distributed tracing integration for end-to-end latency visibility
• Scaling Strategies: Sharding hot keys with Registry, hash ring distribution, and preparing for cluster-wide coordination patterns

Read the full article on Freshcode.