Scaling to 1.2 Billion Daily API Requests with Caching at RevenueCat

RevenueCat handles over 1.2 billion daily API requests with a caching solution built using Memcached. Key goals for their caching infrastructure include low latency, keeping cache servers active and full, and maintaining data consistency. They use techniques like pre-established connections, a fail-fast approach, mirrored and gutter pools, and local caching to optimize performance and reliability. Handling hot keys and avoiding thundering herds are essential strategies to maintain system stability. RevenueCat also employs a systematic approach for cache server migrations and maintaining data consistency to ensure smooth operations.