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Enable Ruby YJIT

Prerequisite

  • Ruby 3.2
  • ruby:3.2 docker image

Enable YJIT

You can enable Ruby YJIT by adding the RUBY_YJIT_ENABLE environment variable:

$ docker run ruby:3.2 bash -c "RUBY_YJIT_ENABLE=1 ruby -e 'p RubyVM::YJIT.enabled?'"
true

$ docker run ruby:3.2 bash -c "ruby -e 'p RubyVM::YJIT.enabled?'"
false

Benchmark

Let’s benchmark a simple Ruby script to check how fast YJIT is.

Here is a simple recursive Fibonacci sequence in Ruby:

def fibonacci(n)
  return n if n == 0 || n == 1

  fibonacci(n-2) + fibonacci(n-1)
end

puts fibonacci(45)

Disable YJIT

$ time ruby fibo.rb
1134903170

real	2m28.208s
user	2m28.174s
sys	0m0.029s
$ time ruby fibo.rb
1134903170

real	2m28.895s
user	2m28.853s
sys	0m0.034s
$ time ruby fibo.rb
1134903170

real	2m29.092s
user	2m29.051s
sys	0m0.034s

Enable YJIT

$ time RUBY_YJIT_ENABLE=1 ruby fibo.rb
1134903170

real	0m20.768s
user	0m20.738s
sys	0m0.029s
$ time RUBY_YJIT_ENABLE=1 ruby fibo.rb
1134903170

real	0m20.769s
user	0m20.737s
sys	0m0.031s
$ time RUBY_YJIT_ENABLE=1 ruby fibo.rb
1134903170

real	0m20.818s
user	0m20.785s
sys	0m0.030s

Comparison

Ruby 3.2 without YJIT Ruby 3.2 with YJIT Result
2m30s 20s YJIT is 7x faster

References
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