This document discusses using JRuby to run Ruby on Rails applications on the Java Virtual Machine. It provides instructions for installing JRuby and running Rails applications with it. It also describes how to deploy Rails applications to Java application servers like Tomcat using tools like Warbler. The document demonstrates monitoring and performance tuning Rails applications running on JRuby, and provides a sample blog application deployment to Tomcat as an example.

1. It’s a Bird…
It’s a Plane…
DigitalSonic
No, it’s Superman Oct. 2009

2. How many Rails developers
have Java knowledge?

3. • The Best of JVM
• It’s Just Ruby
• Platform Independent

4. Have a Try
• Download the latest JRuby distribution
• Unpack
• Add the bin path to $PATH or %PATH%
• Test it
jruby –v
jirb
jirb_swing

5. Ruby => JRuby
• ruby  jruby
• C backend libraries  Java backend libraries
• …
• gem  jruby –S gem
• rake  jruby –S rake
• rails  jruby –S rails

6. Ruby on Rails => JRuby on Rails
adapter: mysql
mongrel
RMagick
…
adapter: jdbcmysql
mongrel-jruby
RMagick4J
…

7. Both Rails and Java EE projects are
running in the same Java AS?

8. Warbler
• Warbler is a gem
that makes a .war
file out of a Rails,
Merb, or Rack-based
application.
http://kenai.com/projects/warbler

9. Rails in Java AS
• Tomcat
• Jetty (jetty-rails)
• Glassfish v2 / v3 (gem)
• JBoss (JBoss-Rails)
• …

10. Rails in Java AS (cont.)
• Connection Pool
• Load-Balance
• Larger JVM Memory Size
• Server JVM
• Latest JDK
• Sun JDK / BEA JRockit ?

11. Showcase: Blog
• Getting Started with Rails
http://guides.rubyonrails.org/getting_started.html
• Step by Step
jruby -S rails blog
Modify database settings
jruby -S warble config
Modify config/warble.rb
jruby -S warble war
Deploy into Tomcat

12. Showcase: Blog (cont.)

13. Showcase: Monitor
• Tomcat Monitor Tools
PSI Probe (Lambda Probe)
Hyperic HQ
• VM Monitor Tools
JConsole
VisualVM
JRockit Mission Control

14. Showcase: Monitor (cont.)

15. Showcase: Monitor (cont.)

16. Showcase: Simple Tuning
• VM
 -Xmx768m -Xms768m -Xmn256m -XX:MaxPermSize=128m -
XX:PermSize=128m
• Tomcat Connector
 maxThreads="1024" minSpareThreads="32" maxSpareThreads="128"
enableLookups="false"
• JNDI Connection Pool
 For my laptop only, not for production environment
 Some parameters are set without measurement

17. Showcase: Simple Tuning (cont.)
Time Taken For Tests (s)
200 185.817
180
160 rails 2.2.2
140 activerecord-jdbc-adapter 0.9.2
120 106.742
100
jdbc-mysql 5.0.4
80 64.735 warbler 0.9.14
60
40
18.561 12.367 6.748
20
0
Mongrel Tomcat Tomcat-Optimized
ab -n 100 -c 10 (ms)
Total n100 c10 Total n1000 c100
2500 2396
2000 1784 1805
Ubuntu 8.10, kernel 2.6.27-14-generic
1500
JDK 1.6.0 Update 10 1202
JRuby 1.3.1 1000 786
641
Apache Tomcat 6.0.20
500 266
Mongrel 1.1.5 241
142
0
Min Avg Max
Mongrel Tomcat Tomcat-Optimized

18. Reference
• http://jruby.org
• http://rubyonrails.org/
• http://kenai.com/projects/jruby/
• Practical JRuby on Rails Web 2.0 Projects
• JRuby Cookbook

19. Q&A