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Inline Class#new
Feature #21254
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Implement Class#new in Ruby
class Class
def new(...)
Primitive.attr! :c_trace
Primitive.pop!(
Primitive.send_delegate!(
Primitive.dup!(Primitive.rb_class_alloc2), :initialize, ...))
end
end
class BasicObject
def initialize
Primitive.attr! :c_trace
nil
end
end
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Class#new ➡ Ruby
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Inline Class#new
Feature #21254
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Instructions
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Before
> ruby --dump=insns -e'Object.new'
== disasm: #@-e:1 (1,0)-(1,10)>
0000 opt_getconstant_path ( 1)[Li]
0002 opt_send_without_block
0004 leave
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After
> ./miniruby --dump=insns -e'Object.new'
== disasm: #@-e:1 (1,0)-(1,10)>
0000 opt_getconstant_path ( 1)[Li]
0002 putnil
0003 swap
0004 opt_new , 11
0007 opt_send_without_block
0009 jump 14
0011 opt_send_without_block
0013 swap
0014 pop
0015 leave
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Speedup
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Positional Parameters
Allocations per Second by Ruby version
Allocations Per Second
0
9500000
19000000
28500000
38000000
Number of Parameters
0 1 2 3 4 5 6 7 8 9 10
Ruby 3.5 + inlining
Ruby 3.4
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~1.8x Faster
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Keyword Parameters
Allocations per second by Ruby version
Allocations Per Second
0
10000000
20000000
30000000
40000000
Number of Parameters
0 1 2 3 4 5 6 7 8 9 10
Ruby 3.5+inlining
Ruby 3.4
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3 Keyword Params:
3.2x faster
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10 Keyword Params:
6.2x faster
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Positional Parameters + Varied Classes
Allocations per second by Ruby version
(varying allocated class)
Allocations per Second
0
9500000
19000000
28500000
38000000
Number of Parameters
0 1 2 3 4 5 6 7 8 9 10
Ruby 3.5+Inlining
Ruby 3.4
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Keyword Parameters + Varied Classes
Allocations per second by Ruby version
(varying allocated class)
Allocations Per Second
0
10000000
20000000
30000000
40000000
Number of Parameters
0 1 2 3 4 5 6 7 8 9 10
Ruby 3.5+Inlining
Ruby 3.4
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Downsides
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More memory
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Measure ISeq size
How many bytes does the “alloc” method use?
require "objspace"
def alloc
Object.new
end
m = method(:alloc)
insn = RubyVM::InstructionSequence.of(insn)
puts ObjectSpace.memsize_of(insn)
Ruby 3.5 + inlining:
656 bytes
Ruby 3.4:
544 bytes
+122 Bytes
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Real World Memory Increase (ISeq Only)
0.5% Increase in ISeq Size (Ruby 3.4.2 vs 3.5.0+inline)
irb(main):001> 737191972 - 733354388
=> 3837584
Shopify M
onolith
ISeq
Sizes
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Real World Memory Increase (all memory)
1mb increase total (~4GB heap)
irb(main):001> 3981075617 - 3979926505
=> 1149112
Shopify M
onolith
Total H
eap
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Different Stack Trace
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Stack Trace is Different
Class#new is missing
class Foo
def initialize
puts caller
end
end
def hello
Foo.new
end
hello
> ruby test.rb
test.rb:8:in 'Class#new'
test.rb:8:in 'Object#hello'
test.rb:11:in ''
Ruby 3.4
> ./ruby test.rb
test.rb:8:in 'Object#hello'
test.rb:11:in ''
Ruby 3.5 + inlining
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No Test Failures 😅