Mitigating CDN Cache Misses with Scheduling: An Origin Shield for Billion-QPS Social Platforms

The explosive growth of modern short-video platforms like WeChat Channels — approaching 1.4 billion monthly active users (MAU) while serving over one billion queries per second (QPS) — has exposed fundamental limitations in conventional content delivery network (CDN) architectures, particularly their inability to handle highly dynamic content popularity patterns. The traditional cache-centric approach proves to be catastrophic when faced with ephemeral content exhibiting a "million-item waist" distribution. This phenomenon results in severe cache pollution (manifesting as 5–40% origin miss ratios) and introduces prohibitive back-to-origin bandwidth costs. Our TritonFlow overcomes these challenges by introducing access point scheduling as a novel origin traffic compensator, which reduces the operational cost of back-to-origin fetches by enhancing CDN cache affinity. Through analysis of production traces (peak >1B QPS), we demonstrate that TritonFlow reduces scheduling fluctuations by 96% and decreases back-to-origin traffic caused by non-compulsory cache misses by 35%, all while maintaining sub-200ms fetch latency.