Serverless servers: Efficient serverless Node.js with in-function concurrency

What this post added

Introduces in-function concurrency for Vercel Functions, allowing a single instance to handle multiple calls simultaneously. This optimizes efficiency by leveraging idle time, potentially cutting costs by up to 50%. The implementation involves a Rust-powered runtime and a function load balancer to manage concurrent invocations. This breaks away from the traditional one-to-one mapping of invocation to compute, improving efficiency for interactive workloads like server-rendering, APIs, and AI applications.