The Backend Engineering Show with Hussein Nasser Cloudflare's 150ms global cache purge | Deep Dive
Oct 18, 2024
Discover how Cloudflare revolutionized its CDN caching with a global cache purge that executes in under 150 ms. The shift from a centralized lazy purge to a decentralized active system showcases remarkable engineering feats. Explore the intricacies of RockDB, peer-to-peer data structures, and how these innovations address previous limitations. Delve into the performance implications of LSM versus BTree and unpack the benefits of immediate purge requests. This deep dive reveals the complexities and clever strategies behind cutting-edge backend engineering.
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CDN Caching and Purging
- Cloudflare's CDN caches content based on request parameters and URLs.
- Users can purge this content globally, which presents a significant challenge.
Old Purge System
- Cloudflare's old centralized purge system relied on a database called Quicksilver.
- This system's lazy purge approach compared cached content with purge requests upon new requests.
TTL and Purging Analogy
- Short TTLs increase server load, while long TTLs necessitate on-demand purging.
- Hussein Nasser explains purging with a reference to "The Purge" movie.