Ruby on Rails — Rails 7.2: Better production defaults, Dev containers, new guides design, and more!

Rails 7.2 comes with better productions defaults to help you build more efficient applications.Starting with YJIT. YJIT is Ruby’s JIT compiler that is available in CRuby since Ruby 3.1. It can provide significant performance improvements for Rails applications, offering 15-25 percent latency improvements.In Rails 7.2, YJIT is enabled by default if running Ruby 3.3 or newer.After careful consideration, investigation, and based on battle-tested experience from applications running in production, we decided to change the default number of threads in Puma from 5 to 3. This change is to improve latency (request response time) by reducing the time Ruby spends waiting for the Global VM Lock (GVL) to release when the thread count is too high.And the default Dockerfile generated by Rails now includes jemalloc to optimize memory allocation.