Ruby 4.0.0 also introduces ZJIT, a new just-in-time compiler intended to be the next generation of YJIT. Built into Ruby’s YARV reference implementation, ZJIT is faster than the interpreter, but not yet as fast as YJIT. Developers are encouraged to experiment with ZJIT, but maybe hold off on deploying it in production for now. Users are advised to stay tuned for Ruby 4.1 ZJIT.
Also in Ruby 4.0.0, Ruby’s parallel execution mechanism, Ractor, has received improvements including a new class, Ractor:port, to address issues pertaining to message sending and receiving, and Ractor.shareable_proc, to make it easier to share Proc objects between Ractors. For performance, many internal data structures in Ractor have been improved to reduce contention on a global lock, thus resulting in better parallelism. Ractors now also share less internal data, resulting in less CPU contention when running in parallel.
Ruby first emerged in 1995. Other features in Ruby 4.0.0 include the following:
