Kino: A high-performance Ractor web server for Ruby 4.0
Kino is a new high-performance web server designed for Ruby 4.0 that utilizes Ractors to achieve true parallel execution. By running code on every CPU core within a single process, it aims to overcome the limitations of the Global VM Lock.
Why it matters
This represents a significant technical advancement for the Ruby ecosystem, potentially allowing for more efficient resource utilization in web applications.
Kino is a high-performance Ractor web server for Ruby 4.0+.
Ruby threads cannot run Ruby code in parallel, so production setups fork a process per core and pay for each copy in memory. Kino runs your code on every core in one small process . A Rust (tokio + hyper) front-end owns the network, parallel Ractors run your Rack 3 app, and a threaded fallback mode runs everything else, Rails included.
N.B.: Ractors are officially experimental in Ruby 4.0, and so is this server. The threaded mode is solid. Still, Kino aims to be the best way to experiment with Ractors today—and the best Ractor server when they become stable.
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