YARV (Yet another Ruby VM) is a bytecode interpreter that was developed for the Ruby programming language by Koichi Sasada. The goal of the project was to greatly reduce the execution time of Ruby programs.
Since YARV has become the official Ruby interpreter for Ruby 1.9, it is also named KRI (Koichi's Ruby Interpreter).
Benchmarks by rubychan.de showed significant increases in performance. Benchmarks by Antonio Cangiano showed an average four times speed improvement over the original interpreter. Both evaluations comprised a mix of mostly synthetic benchmarks.
On January 1, 2007, YARV was merged into the Ruby Subversion repository.
Ruby creator Yukihiro Matsumoto fully merged YARV into Ruby 1.9.0 which was released December 26, 2007. From this point onwards YARV became the official Ruby interpreter, replacing the one developed by Matsumoto.