> Using a JVM destroys any perspective of cheap and easy deveployement.
I doubt that. The fact that jruby is close to bug-by-bug compatibility means that for most projects you can go and develop on mri or rubinius for fast development and use jenkins/travis/... to run your testsuite against jruby. You can then do integration tests as well as staging on jruby to catch anything your testsuite didn't catch. I've seen more than one large project take that course of action and do just fine.
Deployment on jruby isn't any harder than deployment on any other ruby. It's still "puma start" or whichever server you chose. You can however package your app in a war use a standard servlet container such as tomcat or jetty to deploy, but that's strictly optional.
I doubt that. The fact that jruby is close to bug-by-bug compatibility means that for most projects you can go and develop on mri or rubinius for fast development and use jenkins/travis/... to run your testsuite against jruby. You can then do integration tests as well as staging on jruby to catch anything your testsuite didn't catch. I've seen more than one large project take that course of action and do just fine.
Deployment on jruby isn't any harder than deployment on any other ruby. It's still "puma start" or whichever server you chose. You can however package your app in a war use a standard servlet container such as tomcat or jetty to deploy, but that's strictly optional.