Instant Purge: invalidating cached content in under 150ms

This post details the technical improvements made to Cloudflare's cache purge system, specifically focusing on reducing latency for flexible purges (by tags, hostnames, and prefixes). The core problem addressed was the high latency and scalability limitations of the previous 'lazy purge' system, which relied on Quicksilver for distribution and required significant storage for purge history. The new system is designed to be 'coreless compatible' and achieves sub-150ms average global purge latency. The post explains the challenges of flexible purges compared to URL purges, the limitations of the previous Quicksilver-based system, and the need for a new multi-purge mechanism. It highlights the trade-offs involved in avoiding continuous scanning of all disks worldwide and the benefits of the new system in enabling more purge options for all plan types.