Have you ever wondered how class variables (CVARs) in Ruby work? Would you be surprised to learn that their performance becomes increasingly worse as the inheritance chain grows? I’m excited to share that in Ruby 3.1 we fixed the performance of CVARs.
In this talk we'll look at the language design of class variables, learn about how they work, and, deep dive into how we improved their performance in Ruby 3.1 by adding a cache! We'll look at the cache design and real-world benchmarks showing how much faster they are regardless of the size of the inheritance chain.