Anyone scaling jruby tomcat?

ah ah ? Anyon netty a rails app behind apache?

Yes. What specific info are you looking for.

benchmarks - multi-process configuration / multi-interpreter setup / and where the community is with respect to jetty/netty/trinidad etc.

Multi process is automatic with any java app server and does not require
any configuration.
As to benchmarks for which java app server is faster I do not know
off-hand.
We have several cloud deployed load balanced apps running on Trinidad,
which
is based on Tomcat. Trinidad is the present jruby runtime server with
the most development effort - it keeps evolving; before that GlassFish
was
THE app server for jRuby.
Ever so often, depending on the load, we just add or remove a node
to/from the load balanced cluster.