thread-cpu-bound.rb

require 'benchmark'

def fibonacci(n)
  return 0 if n == 0
  return 1 if n == 1
  fibonacci(n-1) + fibonacci(n-2)
end

def without_threads
  (1..30).map { |i| fibonacci(i) }
end

def with_threads
  (1..30).map do |i|
    Thread.new { fibonacci(i) }
  end.each(&:join)
end

puts "Without threads:"
puts Benchmark.measure { without_threads }

puts "With threads"
puts Benchmark.measure { with_threads }