Connection Pool Exhaustion in Mobile Backends

--- title: "HikariCP Tuning That Survived Our 10x Traffic Spike" published: true description: "Fix HikariCP pool exhaustion, tune PgBouncer transaction mode, and apply the correct pool sizing formula for mobile backends under heavy PostgreSQL load." tags: postgresql, kotlin, performance, architecture canonical_url: https://blog.mvpfactory.co/hikaricp-tuning-that-survived-our-10x-traffic-spike --- ## What You Will Learn By the end of this tutorial, you will know how to configure HikariCP so your mobile backend survives a sudden traffic spike without dying at the database connection layer. We will walk through the exact pool settings, PgBouncer transaction mode workarounds, and the sizing formula that took our KMP backend from crashing at 50K concurrent users to handling them cleanly. Real numbers included. ## Prerequisites - A Kotlin (or JVM) backend using HikariCP for connection pooling - PostgreSQL as your database - Basic familiarity with JDBC connection strings - Optional: PgBouncer