Any advantages when running a Rails application on Tomcat+JRuby instead of Mongrel/Passenger?

I want to install a Rails application (Redmine) on my Root Server. Since i'm already planning to run a Tomcat for various Java applications, I'm asking myself (and you) if it makes sense to also let the Rails application run on Tomcat6+JRuby, or if i should extend an (already running) Apache with Passenger 开发者_StackOverflow中文版and run the Rails app "natively".

What Pros and Cons are there between running the Rails app on a "native" Rails server compared to a Java Server+JRuby?

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I'm not a JRuby expert, but I have used it for a couple things recently, and in my opinion the big win with JRuby is the ability to use Java code (including existing Java libraries) in your Ruby code, and the ability for Java to call and/or embed Ruby. (Most of JRuby's documented success stories involve the ability to access Java from Ruby.) Also, it is possible to run JRuby on systems that may be difficult or impossible to get MRI to run on.

There are some differences between MRI and other C-based rubies and JRuby you should be aware of; they are documented on JRuby's wiki.

In my opinion (and others may disagree), if you're already running MRI-ruby based services, etc. and you don't need to access any Java functionality, I would run my Rails app on MRI.