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

Vercel has introduced a new version of Vercel Functions with in-function concurrency, designed to optimize the efficiency of serverless computing by allowing a single function instance to handle multiple calls simultaneously. This development aims to significantly reduce compute usage and costs, by up to 50%, without impacting latency, making it particularly beneficial for interactive workloads such as server-rendering, APIs, and AI applications. The initiative stems from Vercel's exploration of alternatives to AWS Lambda, which struggled with dynamic workloads due to its one-to-one invocation model. By rewriting the runtime in Rust and establishing a new architecture, Vercel enables serverless functions to better utilize Node.js' concurrency capabilities, thus minimizing idle compute time. This approach has shown promising results among beta users, including Verse, which reported substantial efficiency gains and cost reductions. The feature is now in public beta for Pro and Enterprise customers, with the potential to enhance the efficiency of serverless computing while maintaining the automatic scaling and maintenance-free benefits of Vercel Functions.