jruby

Or to put it another way, you can call C libraries from JRuby, but you can't write C that calls JRuby.

From my experience (moved 2 high load projects to Jruby) transition to JRuby from Ruby is not just changing Ruby version.

I think the big JRuby advantage is actually that by and large code written for MRI Just Works on JRuby.

Groovy is the most JRuby-like of those choices, and probably has far more traction than JRuby because it uses Java syntax and is more heavily promoted.

It's JRuby that must be compatible with MRI (the reference implementation of the language), not the other way around.

So why does JRuby never got as much traction as other jvm langs like clojure, scala, groovy?

Oracle has been investing significant resources in JRuby for some time via the Graal/Truffle research projects.

Is there some kind of vision or plan for how Graal/Truffle fits into the JRuby roadmap?

However, packaging with java, jruby and my application usually turn out to be quite large.

Around 80Mb for a CLI and the startup time for short running programs like CLIs using JRuby can be quite long.

That generally improves performance for JRuby, but there are cases where simply inlining the code together doesn't lead to a measurable increase.

Ok, then why do none of the C app servers work in JRuby?

JRuby defaults to "good for long-running processes" mode, which is great for production but less useful when running short-lived tasks.

It's possible to offer "native extensions" for both MRI and JRuby from a gem by providing both via C and Java extensions, though.

> had never been reported before, despite being largely the same for 9 years I'll admit to encountering weird "er, why is that randomly nil" errors quite regularly with JRuby when load testing webservers, which, er, I've never reported.

Jruby 1.7 simply doesn't work in GAE, and maybe it's not worth making it work there, which I would understand.