JRuby 1.7.21 now available on Heroku

Change effective on 08 July 2015

The Ruby stack now supports JRuby 1.7.21 in 2.0.0 (experimental), 1.9.3, 1.8.7 modes.

To use JRuby 1.7.21 in Ruby 1.9.3 mode, add this to your Gemfile:

ruby '1.9.3', :engine => 'jruby', :engine_version => '1.7.18'

Adjust the ruby value depending on the mode you wish to use.

The JRuby release notes can be found here.