The Digital Press

Ruby's YJIT team at Shopify is developing ZJIT, a next-generation Just-In-Time compiler that aims to improve performance and extensibility in Ruby 3.5. ZJIT introduces a more standard and modular compiler design using an SSA intermediate representation to enable advanced optimizations and easier community contributions.

Why it matters: ZJIT aims to outperform YJIT by enabling optimizations like aggressive inlining and reduced side-exits, improving Ruby execution speed.

The big picture: Moving to a method-based JIT with a textbook compiler architecture could foster broader Ruby core contributions and long-term maintainability.

Current status: ZJIT is early-stage, running microbenchmarks only, targeting feature parity with YJIT by Ruby 3.5 with an opt-in command-line switch.

Commenters say: The community appreciates the move to a more modular design, emphasizes challenges in profiling and optimization, and welcomes Matz's support for upstreaming.