Synchronization Is Bad for Scale

The article discusses the challenges of synchronization in scaling distributed systems, highlighting issues with lock contention and its impact on horizontal scaling. It emphasizes the drawbacks of using locks in high-concurrency environments and presents alternatives like sharding, eliminating locks, consistent hashing, reservation queues, and the Saga Pattern to address synchronization needs efficiently. The author shares experiences from working on a distributed lock service at Mailgun, ultimately abandoning it due to performance limitations. Examples from Mailgun's use of MongoDB demonstrate successful strategies like spreading writes across multiple collections to avoid lock contention and scale efficiently. The article concludes by cautioning against over-reliance on databases for synchronization, advocating for design approaches that embrace eventual consistency and avoid unnecessary locks for improved scalability in distributed systems.