Why JRuby? - RubyConf 2012

Who?

Thomas Charlie
@tom_enebo @headius

JRuby is Ruby! *
1.8.7 & 1.9.3 compatibility
drop-in replacement

* see next slide

*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...

JRuby is Ruby
...and then some?

Announcing JRuby 1.7.0

• Ruby 1.9.3 compat (--1.8 for 1.8.7)
• Java 7 invokedynamic support
• Much awesomeness over 1.6.x

Getting Started

1. Install a JVM
2. rvm install jruby
3. Proﬁt!
% jruby -e ‘puts “wowee”’

JRuby Team

Charlie Tom

Nick Hiro Marcin Nahi Wayne Subbu Douglas Douglas
Douglas
Contribs

Douglas
Douglas Douglas
Douglas Douglas
Other
Douglas
OpenJDK Android
JVMs

JRuby

JRuby
Yoko

JVM
J. Rose

OS (libc, ...)

MRI

nobu
MRI

OS (libc, ...)

We get it for Free!

JVM
J. Rose

Garbage Proﬁled
Native JIT Optimizations
Collection

Native Tooling Cross Platform
Threading

Proﬁle: John Rose
• JVM Engineer since 1997
• Invented C* Language
• JSR 292 lead

JVM over time
(what if we were lazy?)

Go Java Go! 300% for free
JRuby 1.0.3 (bm_red_black_tree.rb)

30

22.5

15

7.5

0
Java 1.4 Java 5 Java 6 Java 7

Go Java Go! 300% for free
JRuby 1.0.3 (bm_red_black_tree.rb) MRI 1.8

30

22.5

15

7.5

0
Java 1.4 Java 5 Java 6 Java 7

JVM is everywhere

• Unix++, Windows
• Exotic platforms: zLinux, OpenVMS, AS/400
• Mobile: Android’s Dalvik, Embedded JVMs

Java bytecode ==
portability

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

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,

No build tools!
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

Libraries
Lucene Neo4j
Selenium

47k libraries in Maven
Hadoop EHCache

JMonkeyEngine
Sitemesh

Languages/Polyglot
Clojure Scala

Jython

Rhino/Nashorn/ Groovy
DynJS (JavaScript)
Micro Focus JVM Visual COBOL

Polyglot

• Use right tool for the right job
• Running in the same VM
• Another dimension of libraries

GC Matters

• Applications grow over time
• Ruby is very object-heavy
• Multiprocess multiplies the problem
• You will eventually have issues

JVM GC

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

OpenJDK GCs

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

Object Homogeneity

• Everything expressed as JVM objects
• Everything shares the same infrastructure
• Including extensions, libraries, etc
• One GC to rule them all
• And one standard memory model

gc_demo.rb

• Heavy GC, mix of old and young
• Steadily growing heap use

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
}

Ruby 1.9.3 JRuby
8000

6000

4000

2000

0
GC count

Ruby 1.9.3 JRuby
10000

1000

100

10

1
GC count

15
Ruby 1.9.3 JRuby

11.25

7.5

3.75

0
GC time %

Ruby 2.0.0 JRuby
Time per GC versus heap usage
300ms

225ms
Time per GC

150ms

75ms

0ms
188KB/29MB 27MB/127MB 199MB/238MB
Heap usage (MRI/JRuby)

Ruby 2.0.0 JRuby
Time per GC versus heap usage

:-(

:-(
User Unhappiness

:-/

:-|

:-)
188KB/29MB 27MB/127MB 199MB/238MB
Heap usage (MRI/JRuby)

Ruby 2.0.0

4,000

3,000
Time Per GC (ms)

2,000

1,000

0
0M 1,250M 2,500M 3,750M 5,000M
Heap Size

Findings

• Lower, more uniform GC times
• Reduced or eliminated pauses
• Very large heaps are no problem
• Predictable, consistent experience

Real Parallellism

• Ruby thread = JVM thread = native thread
• One process can use all cores
• One server can handle all requests

require 'benchmark'

ary = (1..1000000).to_a

loop {
    10.times {
      ary.each {|i|}
    }
  }
}

require 'benchmark'

ary = (1..1000000).to_a

loop {
    (1..10).map {
      Thread.new {
        ary.each {|i|}
      }
    }.map(&:join)
  }
}

Ruby 1.9 Ruby 1.9
unthreaded threaded

Ruby 1.9 Ruby 1.9
unthreaded threaded

JRuby
unthreaded

Ruby 1.9 Ruby 1.9
unthreaded threaded

JRuby JRuby
unthreaded threaded

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

Nonlinear?

• More work means more objects
• Allocation/GC needs memory bandwidth
• No different from multi-process

Profiling

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

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

VisualVM

• CPU, memory, thread monitoring
• CPU and memory proﬁling
• VisualGC
• Heap analysis

JavaFX straight port

Simple Clock

@minute_hand = Path.new.tap do |mh| Draw minute hand
mh.setFill(Color::BLACK)
mh.getElements.add MoveTo.new(4, -4)
mh.getElements.add ArcTo.new(-1, -1, 0, -4, -4, false, false)
mh.getElements.add LineTo.new(0, -radius)
mh.getTransforms.add Rotate.new
end
Implement Java Event
class Refresher
include EventHandler handler
def handle(event); event.source.refresh; end
end
refresh timeline every 1s
Timeline.new.tap do |time|
time.setCycleCount Timeline::INDEFINITE
time.getKeyFrames.add(Keyframe.new(Duration.millis(1000)),
Refresher.new)
time.play
end

getFooBar -> fooBar
@minute_hand = Path.new.tap do |mh|
mh.setFill(Color::BLACK) was getElements
mh.elements.add MoveTo.new(4, -4)
mh.elements.add ArcTo.new(-1, -1, 0, -4, -4, false, false)
mh.elements.add LineTo.new(0, -radius)
mh.transforms.add Rotate.new
end was getTransforms
class Refresher
include EventHandler
end

time.setCycleCount Timeline::INDEFINITE
time.keyFrames.add(Keyframe.new(Duration.millis(1000)),
Refresher.new)
time.play
end was getKeyFrames

setFoo(a) -> foo = a
mh.fill = Color::BLACK was setFill
end

class Refresher
end

was setCycleCount
time.cycleCount = Timeline::INDEFINITE
time.keyFrames.add(Keyframe.new(Duration.millis(1000)),
Refresher.new)
time.play
end

camelCase -> camel_case
mh.fill = Color::BLACK
end

class Refresher
end

Timeline.new.tap do |time| was cycleCount
time.cycle_count = Timeline::INDEFINITE
time.key_frames.add(Keyframe.new(Duration.millis(1000)),
Refresher.new)
time.play
end was keyFrames

Procs as interfaces
end No more extra class
time.key_frames.add Keyframe.new(Duration.millis(1000)) {refresh}
time.play
end

Common Adornments
‘add’ becomes ‘<<‘
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

time.key_frames << Keyframe.new(Duration.millis(1000)) {refresh}
time.play
end

Purugin

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

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

Pimping a side-project

https://github.com/enebo/Purugin

Native Extensions Suck
“Look, nobody enjoys
shooting penguins, but if
you have to shoot penguins,
well, you might as well
enjoy it.”
- Free Waterfall Sr.

Flowchart of Shame
Can I write it in Ruby? Script Java?
no
yes no

Does it need Can I use FFI?
to be n times
faster? no
no
Native Extension

Java Native Extensions

• Written in Java
• Have same performance as Java
• Use same GC as JRuby
• First Class Citizens

Go JRuby Go!
OpenJDK 8 (bm_red_black_tree.rb)

8

6

4

2

0
1.0.3 1.1.6 1.4.0 1.5.6 1.6.8 1.7.0

Severe gains???

9
Severe perf bottleneck(s)
6.75

4.5

2.25

0
1.0.3 1.1.6 1.4.0 1.5.6 1.6.8 1.7.0

1.0.3 & red_black_tree
-J-verbose:gc
[GC (Allocation Failure) 223608K->96408K(330752K), 0.0159780 secs]
8.1s [GC (Allocation Failure) 205112K->108920K(334400K), 0.0187580 secs]
+28 more

8.4s [GC (Allocation Failure) 306948K->208316K(335680K), 0.0188120 secs]
[Full GC (Ergonomics) 208316K->54991K(352256K), 0.2709750 secs]
+28 more

Moar Objects!

1.7.0 & red_black_tree
-J-verbose:gc
0.963s
0.968s
0.968s
0.99s


3

2.25

1.5

0.75

0
1.1.6 1.4.0 1.5.6 1.6.8 1.7.0


3

JVM Feature!
2.25

1.5

0.75

0
1.1.6 1.4.0 1.5.6 1.6.8 1.7.0

Performance

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

How to Optimize Ruby
• Do less work
• Reduce dispatch and call overhead
• Reduce memory overhead
• Find static patterns
• Proﬁle running code
• Emit optimized version with guards

JVM Optimizations
• Proﬁling
• Watch code, optimize hottest paths
• Inlining
• Combine code, optimize as a whole
• Escape analysis
• Eliminate transient objects

def foo; Object.new; end
def invoker; foo; end
i = 0
while i < 10000
invoker
i+=1
end

Inline foo into invoker
def invoker; Object.new; end
i = 0
while i < 10000
invoker
i+=1
end

Inline invoker into loop

i = 0
while i < 10000
Object.new
i+=1
end

Object is transient

i = 0
while i < 10000

i+=1
end

InvokeDynamic

• Java 7+ feature
• Allows us to teach JVM about Ruby
• Dynamic calls can inline
• Constants become truly constant
• JVM’s best optimizations can work

def foo; 1; end
N.times do
i = 0
while i < 10000
invoker
i+=1
end
end

$ jruby -J-XX:+UnlockDiagnosticVMOptions
-J-XX:+PrintInlining
-J-XX:+PrintCompilation
script.rb
79 1 b java.lang.String::hashCode (55 bytes)
109 2 b java.util.Properties$LineReader::readLine (452 bytes)
@ 48 java.io.Reader::read (9 bytes) never executed
@ 62 java.io.FilterInputStream::read (9 bytes)
@ 303 java.lang.System::arraycopy (0 bytes) (intrinsic)
@ 388 java.io.Reader::read (9 bytes) never executed
....

def foo; 1; end
N.times do
i = 0
while i < 10000
invoker
i+=1
end
end

3321 190 b ruby.__dash_e__::block_0$RUBY$__file__ (83 bytes)
@ 6 org.jruby.RubyFixnum::op_lt (22 bytes) inline (hot)
@ 66 org.jruby.RubyBasicObject::isTrue (15 bytes) inline (hot)
@ 6 ruby.__dash_e__::method__1$RUBY$invoker (9 bytes) inline (hot)
@ 6 ruby.__dash_e__::method__0$RUBY$foo (7 bytes) inline (hot)
@ 5 org.jruby.RubyFixnum::op_plus_one (31 bytes) inline (hot)

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

5

3.75

2.5

1.914 1.806
1.538 1.565
1.25 1.346

0

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

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/

Ruby 1.8.7 Ruby 1.9.3 Ruby 2.0.0 JRuby

100000

75000

50000

25000

19590.7
11439
4750
0
Iterations per second

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!
• JRuby BOF in Room C at 6:30PM

Thank you!

• @headius
• jruby.org
• torquebox.org

Why JRuby? - RubyConf 2012

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Editor's Notes