How Fluid compute works on Vercel

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This post details how Fluid compute works on Vercel, focusing on the Vercel Functions router's role in coordinating function execution. It explains how the router dynamically assigns requests to instances based on real-time metrics, enabling instances to process multiple concurrent requests. The architectural pattern of instances communicating exclusively through the router via persistent TCP tunnels is highlighted for enhanced security and control. The request lifecycle is broken down into routing, security, and caching; compute selection and execution (prioritizing in-flight and pre-warmed instances); processing and response optimization (including streaming); and adaptive scaling. The cost reduction benefits of Fluid compute, up to 85%, are also emphasized.