JRuby is a Ruby implementation that runs on the Java Virtual Machine (JVM). It allows Ruby code to leverage Java libraries and frameworks and enables deployment on JVM platforms like Android. The JRuby team maintains and improves JRuby, but much of the underlying infrastructure like memory management, threading, and JIT compilation is provided by the JVM, allowing the team to focus on Ruby-specific aspects. JRuby can be used on many platforms and provides access to Java libraries and frameworks, enabling applications to leverage large Java ecosystems.

1. Why JRuby?

2. Me
• Charles Oliver Nutter
• @headius
• Java developer since 1996
• JRuby developer since 2006
• Red Hat / JBoss polyglot group

3. What is JRuby?

6. Ruby on JVM
• Core classes and runtime in Java
• Moving parts to Ruby over time
• Standard command line
• 1.8 and 1.9 compatible
• 1.9 default in JRuby 1.7
• Drop in replacement for MRI*

7. *caveats
• Weak but improving low-level UNIX stuff
• No C extension support
• Not maintained...off by default in 1.7
• Some features differ or unavailable
• ObjectSpace, trace funcs, callcc, fork...

8. JRuby 1.7
• Ruby 1.9.3 mode by default
• Many 1.9 compat fixes
• Numerous perf improvements
• Java 7 invokedynamic support
• Beginning of new optimizing compiler

9. Getting Started
• Need a JVM...
• rvm install jruby
• rvm install jruby-1.7.0-RC1
• Download manually
• Unpack, edit PATH, done

10. Try it Out

11. def fractal_flipflop
w, h = 44, 54
c = 7 + 42 * w
a = [0] * w * h
g = d = 0
f = proc do |n|
a[c] += 1
o = a.map {|z| " :#"[z, 1] * 2 }.join.scan(/.{#{w * 2}}/)
puts "f" + o.map {|l| l.rstrip }.join("n")
d += 1 - 2 * ((g ^= 1 << n) >> n)
c += [1, w, -1, -w][d %= 4]
end
1024.times do
!!(!!(!!(!!(!!(!!(!!(!!(!!(true...
f[0])...f[1])...f[2])...
f[3])...f[4])...f[5])...
f[6])...f[7])...f[8])
end
end

12. def fractal_flipflop
w, h = 44, 54
c = 7 + 42 * w
a = [0] * w * h
g = d = 0
f = proc do |n|
a[c] += 1
o = a.map {|z| " :#"[z, 1] * 2 }.join.scan(/.{#{w * 2}}/)
puts "f" + o.map {|l| l.rstrip }.join("n")
d += 1 - 2 * ((g ^= 1 << n) >> n)
c += [1, w, -1, -w][d %= 4]
end
1024.times do
!!(!!(!!(!!(!!(!!(!!(!!(!!(true...
f[0])...f[1])...f[2])...
f[3])...f[4])...f[5])...
f[6])...f[7])...f[8])
end
end

13. JRuby is the best*
Ruby runtime

14. The Team

15. JRuby Team

16. JRuby Team
Charlie

17. JRuby Team
Charlie Tom
Nick Hiro Marcin Nahi Wayne Subbu Douglas Douglas
Douglas
Contribs

18. JRuby Team
Charlie Tom
Nick Hiro Marcin Nahi Wayne Subbu Douglas Douglas
Douglas
Contribs
Douglas
Douglas Douglas
Douglas Douglas
Douglas Douglas
Other
Douglas
OpenJDK Android J9
JVMs

19. JRuby Structure
JRuby
Bytecode Core Java
Parser
JIT Classes Integ
JVM
Native
Threads GC C API
JIT

20. JRuby Structure
JRuby
Bytecode Core Java
Parser
JIT Classes Integ
JRuby team can focus on implementing JRuby.

21. JRuby Team Doesn’t
Have to Work On*
• Memory allocation • Native JIT
• Garbage collectors • Tooling
• Native threading • Server environments
• Cross-platform • Native extensions
• Mobile/Embedded VMs

22. We could stop working
on JRuby and it would
continue to get faster.

23. Platforms

24. Systems
• Best Ruby on Windows?
• Exotic platforms: zLinux, OpenVMS, AS/400
• Android’s Dalvik
• Embedded JVMs

27. actionmailer-javamail, active_documentum, activerecord-jdbc-adapter, activerecord-jdbcdbf-adapter, activerecord-jdbcderby-adapter, activerecord-jdbch2-
adapter, activerecord-jdbchsqldb-adapter, activerecord-jdbcmssql-adapter, activerecord-jdbcmysql-adapter, activerecord-jdbcpostgresql-adapter, activerecord-
jdbcsqlite3-adapter, activerecord-netezza-adapter, activerecord-vertica-adapter, akephalos, akephalos-nerian, akephalos2, akka-actor-jars, akka-remote-jars,
akubra_llstore_migrate, Antwrap, async-http-client-jars, atomic, atoulme-Antwrap, autotest-java, bbrowning-deltacloud-client, bbrowning-deltacloud-core,
bcrypt-ruby, bee_java, berkeley-db-java-jars, bert, bio-maf, blockenspiel, boc, bond, bosdk, bouncy-castle-java, boxed-geminabox, brute-fuzzy, bryanl-gherkin,
bson, buby, buildr, buildr-resolver, buildrizpack, butternut, capistrano-java, capybara-java_script_lint, carrierwave-neo4j, carrierwave_imagevoodoo, cassandra-
jars, chrest, cloby, commons-io-jars, concurrently, contextual, coupler, cucumber-java, cucumber-jvm, cuke4duke, cuuid, dm-ldap-adapter, dm-lucene-adapter,
do-jdbc_sqlserver, do_derby, do_h2, do_hsqldb, do_jdbc, do_mysql, do_openedge, do_oracle, do_postgres, do_sqlite3, do_sqlserver, doubleshot, dripdrop,
dubious, duby, engineyard-visualvm, epall-limelight, errbit_zmq_handler, eurydice, euston, euston-daemons, euston-eventstore, euston-projections, euston-
rabbitmq, euston-websites, eventmachine, excemel, faye-websocket, ffi, fig, file-find, fishwife, foreman, forkit, forkjoin, gamelan, gemshit, geoip-jars, get_back,
gherkin, glassfish, gravitext-util, gravitext-xmlprod, grizzly, guava-jars, hadoop-find, hashdot-test-daemon, hiredis, hitimes, hope, hostor, hot_bunnies, hourglass,
hpricot, http_parser.rb, inline_javascript, iudex, iudex-async-httpclient, iudex-barc, iudex-brutefuzzy-protobuf, iudex-brutefuzzy-service, iudex-char-detector,
iudex-core, iudex-da, iudex-filter, iudex-html, iudex-http, iudex-http-test, iudex-httpclient-3, iudex-jetty-httpclient, iudex-rome, iudex-simhash, iudex-worker,
ivy-jars, iyyov, jactive_support, java-autotest, java-inline, java2ruby-xmldsig, java_bin, java_inline, java_override, java_properties, java_streamify,
java_testing_guff, javabean_xml, javaclass, javaeye4r, javagems, javajake, javaobj, javaobjs, javaobs, javaparse, javasand, javascript-securehash-rails, javascript-state-
machine-rails, javascript_auto_include, javascript_eraser, javascript_features, javascript_i18n, javascript_localize, javascript_safe_logger,
javascript_util_asset_pack, javascripto, javascripto-rails, jdbc-derby, jdbc-hsqldb, jdbc-jtds, jdbc-openedge, jdbc-openedge-internal, jdbc-postgres, jdbc-sqlite3,
jedis-jars, jena-jruby, jessica, jettr, jetty, jetty-jsp, jgeoip, jms4r, jpdfer, jrack_handlers, jrtm, jruby-activemq, jruby-akka_jars, jruby-elasticsearch_jars, jruby-
httpclient, jruby-launcher, jruby-management, jruby-metrics, jruby-pageant, jruby-vijava, jruby_gc_stats, jruby_sandbox, jruby_threach, jrubyconf-button,
jsmetric4java, json, json-jruby, jsound, kb-activerecord-jdbc-adapter, kirk, kyotocabinet-java, ladle, latex-decode, launchy, libnotify, limelight, linecache, logback,
logback-jars, looksee, lumix, mack-javascript, markdownj, maven_irb_plugin, metrics-core-jars, metrics-java, mguymon-buildr, mikka, mini_aether, mirah,
mirah_model, miso-java, mixology, mm_mq, mongrel, msgpack-idl-java, msgpack-jruby, multimeter, naether, nanoc-javascript-concatenator, neo4j, neo4j-admin,
neo4j-advanced, neo4j-community, neo4j-core, neo4j-enterprise, neo4j-spatial, neo4j-will_paginate, neo4j-wrapper, netty-jars, ning-compress-jars, nio4r,
nokogiri, nokogiri-fitzsimmons, nokogiri-maven, nosqoop4u, ontomde-demo-java5, ontomde-java, ontomde-java-frontend, ontomde-uml2-java, ontomde-uml2-
kbjava, open_nlp, pacer, pacer-dex, pacer-neo4j, pacer-orient, pelops-jars, persvr, pg_array_parser, protobuf-jars, pry, puma, qtjruby-core,
qwirk_active_mq_adapter, qwirk_jms_adapter, rabbitmqadmin-cli, ragweed, rails_javascript_helpers, rakejava, rave, rcov, realityforge-jekyll, realityforge-
jekylltask, redcar-bundles, redcar-clojure, redcar-filter-through-command, redcar-groovy, redcar-icons, redcar-javamateview, redcar-javascript, redcar-mirah,
redcar-svnkit, redcar-xulrunner-win, RedCloth, refinerycms-javascripts, reigns, revo-nokogiri, rika, rjack-async-httpclient, rjack-commons-codec, rjack-
commons-dbcp, rjack-commons-dbutils, rjack-commons-pool, rjack-httpclient-3, rjack-httpclient-4, rjack-icu, rjack-jackson, rjack-jdom, rjack-jets3t, rjack-jetty,
rjack-jetty-jsp, rjack-jms, rjack-jms-spec, rjack-logback, rjack-lucene, rjack-maven, rjack-mina, rjack-nekohtml, rjack-protobuf, rjack-qpid-client, rjack-rome,
rjack-slf4j, rjack-solr, rjack-tarpit, rjack-xerces, rmagick4j, rmodbus, rtm-javatmapi, rtm-majortom, rtm-ontopia, rtm-tinytim, rtm-tmql, rubeus, rubinius-core-
api, ruby-blockcache, ruby-debug-base, ruby-maven, ruby2java, rubydoop, rubyjedi-nokogiri_java, scala-inline, scala-library-jars, scriptty, slf4j, slf4j-jars, slyphon-
zookeeper, slyphon-zookeeper_jar, smackr, smartimage, SNMP4JR, solr_sail, spiegela-jruby-httpclient, sproutcore, spymemcached, sqldroid, steamcannon-
deltacloud-client, steamcannon-deltacloud-core, stilts-stomp-client, supermarket, svm_toolkit, swt, theduke, thick, to-javascript, torquebox-base, torquebox-
cache, torquebox-configure, torquebox-container-foundation, torquebox-core, torquebox-messaging, torquebox-messaging-container, torquebox-naming,
torquebox-naming-container, torquebox-security, torquebox-server, torquebox-vfs, torquebox-web, twitter4j4r, UDJrb, unageanu-javaclass, unimidi, universe-
javascript, url_escape, weakling, webbit-jars, wildnet-jackson, wildnet-netty, wildnet-server, wildsonet-hazelcast, wildsonet-netty, wildsonet-server, wildsonet-
streamer, wrest, wrong, xdojava, xqruby, zookeeper

28. actionmailer-javamail, active_documentum, activerecord-jdbc-adapter, activerecord-jdbcdbf-adapter, activerecord-jdbcderby-adapter, activerecord-jdbch2-
adapter, activerecord-jdbchsqldb-adapter, activerecord-jdbcmssql-adapter, activerecord-jdbcmysql-adapter, activerecord-jdbcpostgresql-adapter, activerecord-
jdbcsqlite3-adapter, activerecord-netezza-adapter, activerecord-vertica-adapter, akephalos, akephalos-nerian, akephalos2, akka-actor-jars, akka-remote-jars,
akubra_llstore_migrate, Antwrap, async-http-client-jars, atomic, atoulme-Antwrap, autotest-java, bbrowning-deltacloud-client, bbrowning-deltacloud-core,
bcrypt-ruby, bee_java, berkeley-db-java-jars, bert, bio-maf, blockenspiel, boc, bond, bosdk, bouncy-castle-java, boxed-geminabox, brute-fuzzy, bryanl-gherkin,
bson, buby, buildr, buildr-resolver, buildrizpack, butternut, capistrano-java, capybara-java_script_lint, carrierwave-neo4j, carrierwave_imagevoodoo, cassandra-
jars, chrest, cloby, commons-io-jars, concurrently, contextual, coupler, cucumber-java, cucumber-jvm, cuke4duke, cuuid, dm-ldap-adapter, dm-lucene-adapter,
do-jdbc_sqlserver, do_derby, do_h2, do_hsqldb, do_jdbc, do_mysql, do_openedge, do_oracle, do_postgres, do_sqlite3, do_sqlserver, doubleshot, dripdrop,
dubious, duby, engineyard-visualvm, epall-limelight, errbit_zmq_handler, eurydice, euston, euston-daemons, euston-eventstore, euston-projections, euston-
rabbitmq, euston-websites, eventmachine, excemel, faye-websocket, ffi, fig, file-find, fishwife, foreman, forkit, forkjoin, gamelan, gemshit, geoip-jars, get_back,
gherkin, glassfish, gravitext-util, gravitext-xmlprod, grizzly, guava-jars, hadoop-find, hashdot-test-daemon, hiredis, hitimes, hope, hostor, hot_bunnies, hourglass,
hpricot, http_parser.rb, inline_javascript, iudex, iudex-async-httpclient, iudex-barc, iudex-brutefuzzy-protobuf, iudex-brutefuzzy-service, iudex-char-detector,
iudex-core, iudex-da, iudex-filter, iudex-html, iudex-http, iudex-http-test, iudex-httpclient-3, iudex-jetty-httpclient, iudex-rome, iudex-simhash, iudex-worker,
ivy-jars, iyyov, jactive_support, java-autotest, java-inline, java2ruby-xmldsig, java_bin, java_inline, java_override, java_properties, java_streamify,
java_testing_guff, javabean_xml, javaclass, javaeye4r, javagems, javajake, javaobj, javaobjs, javaobs, javaparse, javasand, javascript-securehash-rails, javascript-state-
machine-rails, javascript_auto_include, javascript_eraser, javascript_features, javascript_i18n, javascript_localize, javascript_safe_logger,
javascript_util_asset_pack, javascripto, javascripto-rails, jdbc-derby, jdbc-hsqldb, jdbc-jtds, jdbc-openedge, jdbc-openedge-internal, jdbc-postgres, jdbc-sqlite3,
jedis-jars, jena-jruby, jessica, jettr, jetty, jetty-jsp, jgeoip, jms4r, jpdfer, jrack_handlers, jrtm, jruby-activemq, jruby-akka_jars, jruby-elasticsearch_jars, jruby-
No build tools, no native exts required!
httpclient, jruby-launcher, jruby-management, jruby-metrics, jruby-pageant, jruby-vijava, jruby_gc_stats, jruby_sandbox, jruby_threach, jrubyconf-button,
jsmetric4java, json, json-jruby, jsound, kb-activerecord-jdbc-adapter, kirk, kyotocabinet-java, ladle, latex-decode, launchy, libnotify, limelight, linecache, logback,
logback-jars, looksee, lumix, mack-javascript, markdownj, maven_irb_plugin, metrics-core-jars, metrics-java, mguymon-buildr, mikka, mini_aether, mirah,
mirah_model, miso-java, mixology, mm_mq, mongrel, msgpack-idl-java, msgpack-jruby, multimeter, naether, nanoc-javascript-concatenator, neo4j, neo4j-admin,
neo4j-advanced, neo4j-community, neo4j-core, neo4j-enterprise, neo4j-spatial, neo4j-will_paginate, neo4j-wrapper, netty-jars, ning-compress-jars, nio4r,
nokogiri, nokogiri-fitzsimmons, nokogiri-maven, nosqoop4u, ontomde-demo-java5, ontomde-java, ontomde-java-frontend, ontomde-uml2-java, ontomde-uml2-
kbjava, open_nlp, pacer, pacer-dex, pacer-neo4j, pacer-orient, pelops-jars, persvr, pg_array_parser, protobuf-jars, pry, puma, qtjruby-core,
qwirk_active_mq_adapter, qwirk_jms_adapter, rabbitmqadmin-cli, ragweed, rails_javascript_helpers, rakejava, rave, rcov, realityforge-jekyll, realityforge-
jekylltask, redcar-bundles, redcar-clojure, redcar-filter-through-command, redcar-groovy, redcar-icons, redcar-javamateview, redcar-javascript, redcar-mirah,
redcar-svnkit, redcar-xulrunner-win, RedCloth, refinerycms-javascripts, reigns, revo-nokogiri, rika, rjack-async-httpclient, rjack-commons-codec, rjack-
commons-dbcp, rjack-commons-dbutils, rjack-commons-pool, rjack-httpclient-3, rjack-httpclient-4, rjack-icu, rjack-jackson, rjack-jdom, rjack-jets3t, rjack-jetty,
rjack-jetty-jsp, rjack-jms, rjack-jms-spec, rjack-logback, rjack-lucene, rjack-maven, rjack-mina, rjack-nekohtml, rjack-protobuf, rjack-qpid-client, rjack-rome,
rjack-slf4j, rjack-solr, rjack-tarpit, rjack-xerces, rmagick4j, rmodbus, rtm-javatmapi, rtm-majortom, rtm-ontopia, rtm-tinytim, rtm-tmql, rubeus, rubinius-core-
api, ruby-blockcache, ruby-debug-base, ruby-maven, ruby2java, rubydoop, rubyjedi-nokogiri_java, scala-inline, scala-library-jars, scriptty, slf4j, slf4j-jars, slyphon-
zookeeper, slyphon-zookeeper_jar, smackr, smartimage, SNMP4JR, solr_sail, spiegela-jruby-httpclient, sproutcore, spymemcached, sqldroid, steamcannon-
deltacloud-client, steamcannon-deltacloud-core, stilts-stomp-client, supermarket, svm_toolkit, swt, theduke, thick, to-javascript, torquebox-base, torquebox-
cache, torquebox-configure, torquebox-container-foundation, torquebox-core, torquebox-messaging, torquebox-messaging-container, torquebox-naming,
torquebox-naming-container, torquebox-security, torquebox-server, torquebox-vfs, torquebox-web, twitter4j4r, UDJrb, unageanu-javaclass, unimidi, universe-
javascript, url_escape, weakling, webbit-jars, wildnet-jackson, wildnet-netty, wildnet-server, wildsonet-hazelcast, wildsonet-netty, wildsonet-server, wildsonet-
streamer, wrest, wrong, xdojava, xqruby, zookeeper

29. Servers
• Any Java server can host Ruby
• Trinidad
• Ruby-style CLI server atop Tomcat
• Torquebox
• Full Ruby stack atop JBossAS

30. Ruby App
Sinatra Rails
Rack
Passenger/Thin
Apache/Nginx

31. Ruby App
Sinatra Rails
Rack
Tasks Passenger/Thin
Resque/
DelayedJob Apache/Nginx

32. Ruby App
Sinatra Rails
Rack
Tasks Passenger/Thin Jobs
Resque/
DelayedJob Apache/Nginx crond

33. Ruby App
Sinatra Rails
Rack
Tasks Passenger/Thin Jobs
Resque/
DelayedJob Apache/Nginx crond
Daemons
god/monit

34. TorqueBox AS
Sinatra Rails
Rack Tasks Procs Jobs Daemons
Web Messaging Scheduling Services
JBoss AS
Clustering Load Balancing HA

35. Torquebox
• Rack-compatible • Server management
• Database connectivity • Clustering
• Background daemons • In and out-process cache
• Scheduled jobs • Web sockets
• Messaging • Authentication
• Asynchronous tasks • XA Transactions

36. Torquebox
• Rack-compatible • Server management
• Database connectivity • Clustering
• All R
Background daemons • In and out-process cache
• Scheduled jobs
uby • Web sockets
• Messaging
APIs
• Authentication
• Asynchronous tasks • ! XA Transactions

37. Ruby-friendly Config
TorqueBox.configure do
ruby do ruby:
version "1.9" version: 1.9
compile_mode "off" compile_mode: off
debug false debug: false
interactive true interactive: true
profile_api true profile_api: true
end
end

38. Messaging
application:
TorqueBox.configure do ..
... queues:
queue '/queues/my_app_queue' /queues/my_app_queue:
topic '/queues/my_app_topic'
end topics:
/queues/my_app_topic:

39. Messaging
queue = fetch('/queues/foo')
queue.publish "A text message"
topic = fetch('/topics/foo')
topic.publish "A text message"
queue = TorqueBox::Messaging::Queue.new('/queues/foo')
message = queue.receive
topic = TorqueBox::Messaging::Topic.new('/topics/foo')
message = topic.receive

40. Libraries

41. Libraries
• 340k versioned jars in Maven central
• Compare to 35k gems in RubyGems.org
• Vast majority have no native code
• All usable from JRuby

44. JavaFX
• Scene graph + optimized graphics
• Normal Java library now
• R.I.P. JavaFX Script
• jrubyfx, other projects to wrap it

45. @minute_hand = Path.new.tap do |mh|
mh.fill = Color::BLACK
mh.elements << MoveTo.new(4, -4)
mh.elements << ArcTo.new(-1, -1, 0, -4, -4, false, false)
mh.elements << LineTo.new(0, -radius)
mh.transforms << Rotate.new
end
@hour_hand = Path.new.tap do |hh|
hh.fill = Color::BLACK
hh.elements << MoveTo.new(4, -4)
hh.elements << ArcTo.new(-1, -1, 0, -4, -4, false, false)
hh.elements << LineTo.new(0, -radius/4*3)
hh.transforms << Rotate.new
end

46. Purugin
• Minecraft scripting in JRuby
• Clean and simple DSL
• Purogo: LOGO for Minecraft

47. turtle("four-sided triangle") do |*args|
dim = (args[0] || 5).to_i
block_type = (args[1] || :stone).to_sym
layer do
4.times do |i|
forward dim
turnleft 90
end
end
pivot do
block :none
forward 1
turnleft 90
forward 1
turnup 90
forward 1
turndown 90
turnright 90
block block_type
end
block block_type
(1...dim).step(2).to_a.reverse.each do |i|
dim = i
layer
pivot
end
end

48. Threepence
• Ruby APIs atop Ardor3D library
• Various games atop Ardor3D
• All-in-one clone from Github
• Linux, OS X, Windows, Solaris provided

49. require 'example_base'
class Box < ExampleBase
def initialize
super("Box Example")
end
def init_application
root.layout do
cull_state :back
skybox(:sky, 500, 500, 500, 'images/skybox/blue')
node(:spinning) do
behavior :rotating, Vector3(1, 1, 0.5), 50
box(:left_box, 1, 1, 1) do
behavior :rotating, Vector3(0.5, 1, 1), 50
at 0, 0, -3
texture "images/ardor3d_white_256.jpg"
end.duplicate_as(:right_box) do
at 0, 0, 3
" end
end
end
end
end
Box.start

50. GC

51. GC Matters
• Applications grow over time
• Ruby is very object-heavy
• Multicore MRI multiplies the problem
• You will eventually have issues

52. JVM GC
• Wide array of options
• Many GCs to choose from
• Scales up to massive heaps
• Best GCs in the world!

53. OpenJDK GCs
• Parallel: multi-core stop-the-world
• Concurrent: STW young, concurrent old
• G1: concurrent young and old
• Serial: single-thread STW

54. gc_demo1.rb
• Heavy GC, mix of old and young
• Steadily growing heap use

55. class Simple
attr_accessor :next
end
top = Simple.new
puts Benchmark.measure {
outer = 10
total = 100000
per = 100
outer.times do
total.times do
per.times { Simple.new }
s = Simple.new
top.next = s
top = s
end
end
}

56. Ruby 1.9.3 JRuby
8000
6000
4000
2000
0
GC count

57. Ruby 1.9.3 JRuby
10000
1000
100
10
1
GC count

58. 15
Ruby 1.9.3 JRuby
11.25
7.5
3.75
0
GC time %

59. Ruby 2.0.0 JRuby
Time per GC versus heap usage
300ms
225ms
150ms
75ms
0ms
188KB/29MB 27MB/127MB 199MB/238MB
Heap usage (MRI/JRuby)

60. gc_demo2.rb
• Frequent GC, all young objects
• Steadily growing heap use

61. 10.times do
old_ary = []
10000.times do
old_ary << 'foo'
new_ary = []
100000.times do
new_ary << 'bar'
end
end
puts "looped"
end

62. Ruby 1.9.3 JRuby
5000
3750
2500
1250
0
GC time (ms)

63. JRuby (Concurrent) Ruby 2.0.0
World-stopping GC pause times
0.3s
0.225s
Pause time
0.15s
0.075s
0s
0 5 10 15 20
Seconds since start

64. JRuby (Concurrent) Ruby 2.0.0
World-stopping GC pause times
0.3s
im es
0.225s
useT
Pa
Pause time
0.15s
0.075s
0s
0 5 10 15 20
Seconds since start

65. JRuby (Concurrent) Ruby 2.0.0
World-stopping GC pause times
0.3s
im es
0.225s
useT
Pa
Pause time
0.15s
Use
r Ha
ppi
0.075s nes
s :-
(
0s
0 5 10 15 20
Seconds since start

66. Findings
• Lower, more uniform individual GC time
• Lower overall GC time
• Lower application pause times
• More predictable, consistent apps

67. Threads

68. Real Parallellism
• Ruby thread = JVM thread = native thread
• One process can use all cores
• One server can handle all requests

69. require 'benchmark'
ary = (1..1000000).to_a
loop {
puts Benchmark.measure {
10.times {
ary.each {|i|}
}
}
}

70. require 'benchmark'
ary = (1..1000000).to_a
loop {
puts Benchmark.measure {
(1..10).map {
Thread.new {
ary.each {|i|}
}
}.map(&:join)
}
}

72. Ruby 1.9
unthreaded

73. Ruby 1.9 Ruby 1.9
unthreaded threaded

74. Ruby 1.9 Ruby 1.9
unthreaded threaded
JRuby
unthreaded

75. Ruby 1.9 Ruby 1.9
unthreaded threaded
JRuby JRuby
unthreaded threaded

76. threaded_reverse
Per-iteration time versus thread count
0.8s
0.65s
0.5s
0.35s
0.2s
one thread two threads three threads four threads

77. Nonlinear?
• More work means more objects
• More objects needs memory bandwidth
• No different from multi-process

78. Tools

79. Profiling
• Java profilers
• VisualVM,YourKit, NetBeans, JXInsight
• jruby [--profile | --profile.graph]
• jruby -Xreify.classes=true
• JVM command-line profilers

80. Monitoring
• Java Management Extensions (JMX)
• Gems available for clients and servers
• jconsole and VisualVM
• Most servers provide additional tools
• New Relic, etc have JVM support

81. VisualVM
• CPU, memory, thread monitoring
• CPU and memory profiling
• VisualGC
• Heap analysis

84. Performance

85. Performance
• JRuby compiles Ruby to JVM bytecode
• JVM compiles bytecode to native
• Best JIT technology in the world
• Getting even better with invokedynamic

86. def foo
bar
end
def bar
baz foo bar baz
end
def baz
# ...
end

87. JRuby on Java 5/6
def foo
bar
end
def bar JRuby JRuby
baz foo call bar call baz
end logic logic
def baz
# ...
end
Kills many JVM optimizations

88. JRuby on Java 7
def foo
bar
X X
end
def bar JRuby JRuby
baz foo call bar call baz
end logic logic
def baz
# ...
end
Dynamic call logic built into JVM

89. JRuby on Java 7
def foo
bar
end
def bar
baz foo bar baz
end
def baz
# ...
end
Straight through dispatch path

90. JRuby on Java 7
def foo
bar
end
def bar
baz foo bar baz
end
def baz
# ...
end
Optimizations (like inlining) can happen!

91. def foo; 1; end
def invoker; foo; end
i = 0
while i < 10000
invoker
i+=1
end
0x00000001060a1be0: mov %eax,-0x14000(%rsp)
0x00000001060a1be7: push %rbp
0x00000001060a1be8: sub $0x30,%rsp
0x00000001060a1bec: mov 0x8(%rcx),%r10d
0x00000001060a1bf0: cmp $0xfb7aedc9,%r10d
0x00000001060a1bf7: jne 0x00000001060a1c39
0x00000001060a1bf9: mov %rcx,%r10
0x00000001060a1bfc: mov 0x10(%r10),%ebp
0x00000001060a1c00: cmp $0xfed77602,%ebp
0x00000001060a1c06: jne 0x00000001060a1c1e
0x00000001060a1c08: movabs $0x7f6bf4bb0,%rax
0x00000001060a1c12: add $0x30,%rsp
0x00000001060a1c16: pop %rbp
0x00000001060a1c17: test %eax,-0xec3c1d(%rip)
0x00000001060a1c1d: retq

92. def invoker; 1; end
i = 0
while i < 10000
invoker
i+=1
end
0x00000001060a1be0: mov %eax,-0x14000(%rsp)
0x00000001060a1be7: push %rbp
0x00000001060a1be8: sub $0x30,%rsp
0x00000001060a1bec: mov 0x8(%rcx),%r10d
0x00000001060a1bf0: cmp $0xfb7aedc9,%r10d
0x00000001060a1bf7: jne 0x00000001060a1c39
0x00000001060a1bf9: mov %rcx,%r10
0x00000001060a1bfc: mov 0x10(%r10),%ebp
0x00000001060a1c00: cmp $0xfed77602,%ebp
0x00000001060a1c06: jne 0x00000001060a1c1e
0x00000001060a1c08: movabs $0x7f6bf4bb0,%rax
0x00000001060a1c12: add $0x30,%rsp
0x00000001060a1c16: pop %rbp
0x00000001060a1c17: test %eax,-0xec3c1d(%rip)
0x00000001060a1c1d: retq

93. i = 0
while i < 10000
1
i+=1
end
0x00000001060a1be0: mov %eax,-0x14000(%rsp)
0x00000001060a1be7: push %rbp
0x00000001060a1be8: sub $0x30,%rsp
0x00000001060a1bec: mov 0x8(%rcx),%r10d
0x00000001060a1bf0: cmp $0xfb7aedc9,%r10d
0x00000001060a1bf7: jne 0x00000001060a1c39
0x00000001060a1bf9: mov %rcx,%r10
0x00000001060a1bfc: mov 0x10(%r10),%ebp
0x00000001060a1c00: cmp $0xfed77602,%ebp
0x00000001060a1c06: jne 0x00000001060a1c1e
0x00000001060a1c08: movabs $0x7f6bf4bb0,%rax
0x00000001060a1c12: add $0x30,%rsp
0x00000001060a1c16: pop %rbp
0x00000001060a1c17: test %eax,-0xec3c1d(%rip)
0x00000001060a1c1d: retq

94. i = 0
while i < 10000
i+=1
end
0x00000001060a1be0: mov %eax,-0x14000(%rsp)
0x00000001060a1be7: push %rbp
0x00000001060a1be8: sub $0x30,%rsp
0x00000001060a1bec: mov 0x8(%rcx),%r10d
0x00000001060a1bf0: cmp $0xfb7aedc9,%r10d
0x00000001060a1bf7: jne 0x00000001060a1c39
0x00000001060a1bf9: mov %rcx,%r10
0x00000001060a1bfc: mov 0x10(%r10),%ebp
0x00000001060a1c00: cmp $0xfed77602,%ebp
0x00000001060a1c06: jne 0x00000001060a1c1e
0x00000001060a1c08: movabs $0x7f6bf4bb0,%rax
0x00000001060a1c12: add $0x30,%rsp
0x00000001060a1c16: pop %rbp
0x00000001060a1c17: test %eax,-0xec3c1d(%rip)
0x00000001060a1c1d: retq

95. 0x00000001060a1be0: mov %eax,-0x14000(%rsp)
0x00000001060a1be7: push %rbp
0x00000001060a1be8: sub $0x30,%rsp
0x00000001060a1bec: mov 0x8(%rcx),%r10d
0x00000001060a1bf0: cmp $0xfb7aedc9,%r10d
0x00000001060a1bf7: jne 0x00000001060a1c39
0x00000001060a1bf9: mov %rcx,%r10
0x00000001060a1bfc: mov 0x10(%r10),%ebp
0x00000001060a1c00: cmp $0xfed77602,%ebp
0x00000001060a1c06: jne 0x00000001060a1c1e
0x00000001060a1c08: movabs $0x7f6bf4bb0,%rax
0x00000001060a1c12: add $0x30,%rsp
0x00000001060a1c16: pop %rbp
0x00000001060a1c17: test %eax,-0xec3c1d(%rip)
0x00000001060a1c1d: retq

97. JRuby/Java 6 JRuby/Java 7

98. JRuby/Java 6 JRuby/Java 7
Times Faster than Ruby 1.9.3
5
3.75
2.5
1.25
0
base64 richards neural mandelbrot redblack

99. JRuby/Java 6 JRuby/Java 7
Times Faster than Ruby 1.9.3
5
3.75
2.5
1.914 1.806
1.538 1.565
1.25 1.346
0
base64 richards neural mandelbrot redblack

100. JRuby/Java 6 JRuby/Java 7
Times Faster than Ruby 1.9.3
5
4.226 4.32
3.75
3.66
3.44
2.5 2.658
1.914 1.806
1.538 1.565
1.25 1.346
0
base64 richards neural mandelbrot redblack

101. smooth_sort
# Original Author: Keith Schwarz (htiek@cs.stanford.edu)
#
# Translated to Ruby by Chuck Remes (chuckremes on github)
#
# An implementation of Dijkstra's Smoothsort algorithm, a modification of
# heapsort that runs in O(n lg n) in the worst case, but O(n) if the data
# are already sorted. For more information about how this algorithm works
# and some of the details necessary for its proper operation, please see
#
# http://www.keithschwarz.com/smoothsort/

102. Ruby 1.9.3 JRuby Rubinius MacRuby Ruby 1.8.7
100000
75000
50000
90593
57215
25000
18376
11439
4750
0
Iterations per second

103. And Rails?

107. Your Turn
• Try your apps on JRuby and tell us
• Turn on JRuby in @travisci
• Let us know what you think of JRuby
• Help us make JRuby even better!

108. JRUBY BOOK

110. Thank you!
• @headius
• jruby.org
• torquebox.org