Talk on how JRuby is bringing performance and concurrency to Ruby, delivered at RubyConf India, March 20, 2016 in Kochi, Kerala, India.

1. Ruby Performance
The Last Mile

2. Charles Oliver Nutter
@headius

5. I've spent ten years building

6. I love Ruby

7. I want Ruby to succeed

8. I believe JRuby is the way

9. Do you want performance today?

10. Do you want concurrency today?

11. Do you know JRuby?

13. What you love from Ruby
• Latest Ruby language features
• Mostly-same Ruby standard library
• Pure-Ruby gems work great
• Native gems with JRuby support
• It walks like Ruby, talks like Ruby
• It is Ruby!

14. With the power of the JVM
• Fast JIT to native code
• Fully parallel threading
• Leading-edge garbage collectors
• Access to Java, Scala, Clojure, ...
• But it's still Ruby!

16. Do you know Jay?

17. Matz's Keynote

18. Performance

19. Concurrency

20. By 2020

21. But what about today?

22. Performance

23. What do you optimize for?
• Easy to develop with: short time until first deploy
• Fast startup: good response cycle at command line
• Straight-line performance, many operations per second
• Parallelism: utilize many cores to get more done

24. State of the Art:
Production-quality Rubies

25. Production Quality?
• Support for 99%+ of Ruby language features
• Important parts of standard library
• Runs typical Ruby applications and libraries
• Healthy extension ecosystem
• CRuby, JRuby are the only real options right now

26. CRuby (MRI)
• Up until 1.9, AST interpreter
• YARV bytecode VM introduced for 1.9.0
• GC and performance improvements through 2.x series
• Ruby 2.3 is latest, released in December
• Future work on JIT, GC, happening now

27. JRuby
• Many redesigns since creation in 2001
• AST interpreter until 2007
• Simple AST-to-bytecode JIT until JRuby 9000
• Optimizing compiler with JIT for 9k
• JRuby 9.0.5 is current, 9.1 in a couple weeks
• Next-gen Truffle runtime in the works

28. Lies, damn lies, and
benchmarks

29. CRuby: red/black tree
0
2
4
6
8
1.8.7 1.9.3 2.0 2.1 2.2 2.3

30. CRuby: red/black tree
0
0.625
1.25
1.875
2.5
1.8.7 1.9.3 2.0 2.1 2.2 2.3

31. JRuby: red/black tree
0
1.25
2.5
3.75
5
JRuby 9.1 CRuby 2.3

32. JRuby: red/black tree
0
1.25
2.5
3.75
5
JRuby 9.1 CRuby 2.3

33. JRuby: red/black tree
0
0.6
1.2
1.8
2.4
JRuby 9.1 CRuby 2.3
4x FASTER

34. Ruby Code

35. Ruby Code
Parser
JRuby AST

36. r
JRuby AST
Compiler
JRuby IR

37. er
JRuby IR
JIT
JVM Bytecode

38. What can we do with this?

39. Block Pass-through
def foo(&b)
bar(&b)
end
def bar
yield
end

40. Block Pass-through
loop {
puts Benchmark.measure {
i = 0
while i < 1_000_000
i+=1
foo { }; foo { }; foo { }; foo { }; foo { }
end
}
}

41. Block Passing
0
0.55
1.1
1.65
2.2
CRuby 2.3 JRuby 1.7.24 JRuby 9.1

42. define_method
define_method :add do |a, b|
a + b
end

43. define_method
0
0.25
0.5
0.75
1
CRuby 2.3 JRuby 1.7.24 JRuby 9.1

44. Postfix rescue
foo rescue nil

45. csv.rb Converters
Converters = {
integer: lambda { |f|
Integer(f.encode(ConverterEncoding)) rescue f
},
float: lambda { |f|
Float(f.encode(ConverterEncoding)) rescue f
},

46. Postfix rescue
0
3.5
7
10.5
14
CRuby 2.3 JRuby 9.1

47. 0
3.5
7
10.5
14
CRuby 2.3 JRuby 9.1
Postfix rescue

48. CRuby starts up the fastest

49. JRuby runs the fastest

50. And we're getting faster

51. Concurrency

52. Parallelism

53. Concurrency? Parallelism?
• Parallelism happens on the harder, e.g. multi-core
• Concurrency happens in the software, e.g. Thread API
• You can have concurrency without parallelism
• You can have both with JRuby

55. Parallelism in Ruby
• On CRuby, usually process-level
• Ruby threads prevented from running in parallel
• Extensions, IO can opt to release lock
• On JRuby, usually thread-level
• Ruby thread == JVM thread == OS thread
• Single-process, shared memory

56. A Mailing Queue
• A simple example of concurrency
• For each job, construct an email to send
• Some computation added to make processing heavier
• "Ruby Concurrency and Parallelism: A Practical Tutorial"
https://www.toptal.com/ruby/ruby-concurrency-and-parallelism-a-
practical-primer

57. require "./lib/mailer"
require "benchmark"
puts Benchmark.measure{
(ARGV[0] || 10_000).times do |i|
Mailer.deliver do
from "eki_#{i}@eqbalq.com"
to "jill_#{i}@example.com"
subject "Threading and Forking (#{i})"
body "Some content"
end
end
}

58. POOL_SIZE = (ARGV[0] || 10).to_i
jobs = Queue.new
(ARGV[1] || 10_000).to_i.times{|i| jobs.push i}
workers = (POOL_SIZE).times.map do
Thread.new do
begin
while x = jobs.pop(true)
Mailer.deliver do
...
end
end
rescue ThreadError
end
end
end
workers.map(&:join)

59. CRuby: mailer * 1000
TimeinSeconds
0
37.5
75
112.5
150
synchronous 4 threads 4 forks

60. JRuby: mailer * 1000
0
7
14
21
28
Synchronous 4 Threads

61. JRuby vs MRI
Times Improvement
0
0.85
1.7
2.55
3.4
CRuby Forks JRuby Threads
3.37x
3.09x

62. But Threads are bad, right?

63. Most users will never
Thread.new

64. You'll deploy one Rails server
for your entire site

65. You'll cut your instances
ten times

66. Or maybe 100 times

67. Libraries and frameworks
will Thread.new for you

68. And on JRuby,
you'll have more efficient apps

69. So we're done?

70. Move to JRuby

71. Now your app is fast!

72. Right?

73. It is possible to write
efficient Ruby code

74. But it's very easy to write
inefficient Ruby code

75. Great Features, Hidden Costs
• Blocks are expensive to create, slower than method calls
• case/when is an O(n) cascade of calls
• Singleton classes/methods are costly and hurt method cache
• Literal arrays, hashes, strings have to be constructed, GCed
• Flow-control exceptions can be very expensive and hard to find

76. What happens if your code
does not run fast enough?

77. You need to know your app

78. You need good tools

79. And the JVM has great tools

80. CRuby Tooling
• Basic GC stats built in
• Simple profilers in standard library
• Some third-party tools
• stackprof, ruby-prof, perftools.rb, ...

81. JVM tooling is JRuby tooling

82. JVM Tooling
• Wide range of GCs: parallel, concurrent, realtime, pauseless
• Built-in tools for analyzing GC, JIT, thread, IO, heap
• Built-in remote monitoring via JMX
• Dozens of tools out there for profiling, management, and more

83. VisualVM
• Graphical console into your application
• Monitor GC, threads, CPU usage
• Sampled or full profiling with GUI browser
• Live memory dumping, heap inspection
• Ships with every OpenJDK install

86. Java Mission Control
• Extremely low-overhead application recording
• Analyze results offline in JMC
• GC, CPU, heap events, IO operation all browsable
• Commercial feature, free for development use

90. More on GC
• JVM GCs are incredibly tunable with sensible defaults
• Tools like http://gceasy.io and JClarity give you a deeper view
• These are the best GCs and the best tools in the world

91. Finding Bottlenecks

92. Profiling

93. Profiling Tools
• Command line options: --profile, --sample
• JVM command-line profilers like prof
• Many graphical sampling/complete profiling options
• Flame graphs, stack profilers, you name it!

97. ...and this is just the beginning

98. Wrapping Up

99. Ruby is alive and well

100. CRuby continues to improve

101. Ruby 3 is very exciting

102. JRuby is performance today

103. JRuby is concurrency today

104. JRuby has tools today

105. JRuby makes you happier!

106. Thank You!
Charles Oliver Nutter
headius@headius.com
@headius
http://jruby.org
https://github.com/jruby/jruby