bench_sha256.rb

require 'benchmark'
require 'digest/sha2'
java_import 'java.security.MessageDigest'

def jhex(s)
  md = MessageDigest.getInstance("SHA-256")
  md.update(s.to_java(:String).getBytes)
  md.digest.to_a.pack('C*').unpack('H*')
end

def rhex(s)
  Digest::SHA256.hexdigest(s)
end

srand 42

chars = [*"a".."z", *"A".."Z"]
test = Array.new(200000){
  Array.new(rand(1..2000)){ chars.sample }.join
}

Benchmark.bmbm 20 do |b|
  b.report 'java' do
    test.each{|t| jhex(t) }
  end

  b.report 'ruby' do
    test.each{|t| rhex(t) }
  end
end

output.txt

Rehearsal --------------------------------------------------------
java                   6.860000   0.080000   6.940000 (  4.604000)
ruby                   2.040000   0.000000   2.040000 (  1.794000)
----------------------------------------------- total: 8.980000sec

                           user     system      total        real
java                   4.790000   0.050000   4.840000 (  3.883000)
ruby                   1.620000   0.000000   1.620000 (  1.609000)