● Covered by 1 source · 1 reportMedium impact1 neutral
Kino Web Server for Ruby 4.0+ Uses Ractors for Parallel Performance and Reduced Memory
Key points
- Kino uses Ractors for parallel Ruby code execution on multiple cores.
- It offers 1.5-2x performance improvement over Puma on I/O-light endpoints.
- Kino reduces memory usage by approximately 4-7x compared to Puma.
- It includes production features like graceful drain, crash supervision, and request timeouts.
Introduction of Kino Web Server
Kino is a new high-performance web server designed for Ruby 4.0 and later versions. It addresses the limitation of Ruby's Global Virtual Lock (GVL), which traditionally prevents Ruby threads from executing code in parallel. Kino achieves parallel execution by leveraging Ractors, allowing a single process to utilize all available CPU cores.
Performance and Memory Efficiency
Benchmarks on an 8-core server show Kino's Ractor mode performing 1.5 to 2 times faster than a Puma fork cluster for I/O-light operations, and over 30% faster for CPU-bound tasks. This performance is coupled with substantial memory savings, with Kino using approximately 4 to 7 times less memory than a Puma cluster, depending on the application.
Architecture and Features
Kino employs a Rust-based front-end (using tokio and hyper) to manage network operations, while parallel Ractors handle Rack 3 applications. A threaded fallback mode is available for other applications, including Rails. The server includes production-ready features such as graceful draining, crash supervision, bounded queues with 503 backpressure, request timeouts, and hardened intake mechanisms against slowloris attacks and large requests. It also provides an on_error hook for error tracking and live statistics.
Ractor Integration and Compatibility
Kino's design is specifically built to dispatch requests to Ractors, taking advantage of the rework in Ruby 4.0 that improved Ractor functionality. The server offers a `kino --check` command to identify what prevents an application from running in Ractor mode. While Ractors are experimental in Ruby 4.0, Kino's threaded mode is stable. The server is designed to be familiar to Puma users, adopting a similar `workers × threads` topology and CLI.
✨ This summary was generated by AI from the outlets' reporting listed below. It is not independently verified and may contain errors — check the original sources. How BrevFeed works →
The daily brief
One email each morning: the day's tech stories, clustered across outlets and summarized. No account needed.
One email a day. Unsubscribe in one click, any time.
Today's brief
Spend a few minutes, get the whole day. Every topic's top stories in one hands-free rundown — listen, watch, or read the transcript.
▶ Play today's brief
New every morning, and the back catalogue is archived by date.
Primary sources
GitHub cmc_internal/api GitHub github/collect GitHub yaroslav/kino GitHub _private/browser GitHub get-started/accessibility GitHub open-source/sponsorsReporting from
Kino is a new web server for Ruby 4.0+ that utilizes Ractors to enable parallel execution of Ruby code across multiple CPU cores within a single process, addressing the Global Virtual Lock (GVL) limitation. This approach results in significant performance gains and reduced memory consumption compared to traditional forking servers like Puma.