Improving the Rails
ecosystem
The Rubinius Virtual Machine
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Thanks EY!
2

Be thinking of questions

a_better_ruby
==
a_better_rails
# => true

Brand new code base

Write in ruby first.
Then C if you have to.

If you’re not failing every now
and again, it’s a sign you’re not
doing anything very innovative.
Woody Allen

A work in progrees

Nov. 3: 1.0 preview
End of 07: 1.0

You’re the customer

Help me help you.

Tell me your pain.

Some current pain

Memory usage
Memory

• 1.8 garbage collector is simple, but too simple.
• Rubinius uses modern techniques to decrease
memory usage and increase throughput
Memory
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The forking problem
Memory

In 1.8...
• Start up a mongrel.
• Require all your code.
• fork() the process.
• Watch your memory double.
Memory
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In Rubinius...
• Start up a mongrel.
• Require all your code.
• fork() the process.
• Watch NO change in the memory footprint!
Memory
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Memory change per
additional mongrel instance
1 2 3 4
1.8 rubinius
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Packaging / Deployment

.rba == .jar
.rba == .war
Packaging

• Precompiled code (.rbc)
• Meta data about project
• RDoc
• Assets
Packaging
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Performance

Built for change
Performance

Modern Techniques
• Inline caching
• Pre-compiled code
• JIT (eventually)
Performance
25

3 legged dog turtles space shuttle rubinius
Performance
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Error reporting

Normal Backtraces
An exception has occurred:
User requested termination with Control-C (Interrupt)
Backtrace:
Readline.readline at kernel/core/readline.rb:52
main.__script__ at lib/bin/sirb.rb:78
main.load at kernel/core/compile.rb:78
main.require at kernel/core/compile.rb:129
Array#each at kernel/core/array.rb:526
Integer(Fixnum)#times at kernel/core/integer.rb:19
Array#each at kernel/core/array.rb:526
main.require at kernel/core/compile.rb:112
Array#each at kernel/core/array.rb:526
Integer(Fixnum)#times at kernel/core/integer.rb:19
Array#each at kernel/core/array.rb:526
main.require at kernel/core/compile.rb:111
main.__script__ at kernel/loader.rb:159
Reporting 28

C extensions can
misbehave
Reporting

VALUE test_segfault(VALUE self) {
// Get a pointer to address 4.
char *i = (char*)4;
// Attempt to read from address 4
// which is definitely not allowed.
x = *i;
// Never get this far.
return Qnil;
}
Raises an exception!
Segfault detected in function 0x90a00 (accessing 0x4) (MemorySegmentionError)
SomeExtension#test_segfault at extensions/test/test.c
main.__script__ at extensions/test/test.rb:38
main.load at kernel/core/compile.rb:95
main.__script__ at kernel/loader.rb:122
Reporting

Time lost to segfaults
(in minutes)
1.8 rubinius
200
200
150
100
70
50 30
10
6
2
1 3 5
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Profiling

In 1.8...
• Profiling is instrumented only.
• The speed hit is prohibitive for running in
production mode
Profiling
33

In Rubinius...
• Sampling profiler available always
• Has little to no impact on performance
Profiling
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In my_app.rb
require ‘simple_profile’
profile(:profile1) do
obj.run_slow_method
end
shell# rbx profiler --analyze profile1.results
Profiling
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In environment.rb
require ‘simple_profile’
SimpleProfiler.profile_actions
SimpleProfiler.profile_views
shell# rbx profiler --analyze actions.results
shell# rbx profiler --analyze views.results
Profiling
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Disclaimer

• All statements and numbers and opinions are
only those of Evan Phoenix.
• All statistics are made up, but represent a
general trend.
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Evan Phoenix
evan@fallingsnow.net
ephoenix@engineyard.com
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