I just recently started shifting attention towards deploying Ruby apps atop TorqueBox which of course is built atop Jruby. Hitherto I have been basically performing a bundle install and then tackling each gem along the way to jrubydom, but I've hit a couple gems that have taken me some considerable time to resolve due to needing to reimplement large portions of them.
Is there a way to invoke bundler or rubygems to run through all gems and their deps to test if they require native c extensions and then return such a list? It sure would be nice to tackle some of the more minor items or even to know if it is worthwhile to tackle a project in terms of moving it to jruby.
You can use JRuby Lint for that. It will will check for some gems requiring C extension and even list alternative (based on this list).