How Reddit Works 🔥

Reddit evolved from a single-machine setup to a complex distributed architecture serving 100M daily users. The platform uses job queues for expensive operations like post submissions and voting, implements database partitioning and caching for scalability, and employs Zookeeper for distributed locking. Key architectural decisions include partitioned queues to reduce lock contention, denormalized comment trees for efficient retrieval, and separate databases for posts, votes, and comments to handle massive scale.