user_spec.rb

require 'benchmark'

RSpec.describe User, type: :model do
  context '#benchmark create' do
    let(:users) { FactoryBot.create_list(:user, 5_000) }

    it 'return benchmark' do
      benchmark = Benchmark.measure {
        users
      }

      puts benchmark
    end
  end

  context '#benchmark build' do
    let(:users) { FactoryBot.build_list(:user, 5_000) }

    it 'return benchmark' do
      benchmark = Benchmark.measure {
        users
      }

      puts benchmark
    end
  end

  context '#benchmart items' do
    input = ('a'..'z').map { |letter| [letter, letter] }.to_h

    puts Benchmark.measure {
      5_000_000.times do
        input.map { |key, value| [key.to_sym, value] }.to_h
      end
    }
  end

  context '#benchmark iterate build' do
    it 'return benchmark' do
      benchmark = Benchmark.measure {
        50_000.times do
          FactoryBot.build(:user)
        end
      }

      puts benchmark
    end
  end

  context '#benchmark iterate create' do
    it 'return benchmark' do
      benchmark = Benchmark.measure {
        50_000.times do
          FactoryBot.create(:user)
        end
      }

      puts benchmark
    end
  end

  context '#benchmark cpu intensive task' do
    it 'return benchmark' do
      Benchmark.measure { 10.times { Fibonaci.new.fib(35) } }
    end
  end

  context '#benchmark cpu intensive task on thread' do
    it 'return benchmark' do
      Benchmark.measure {
        threads = []
        10.times do
          threads << Thread.new { Thread.current[:output] = Fibonaci.new.fib(35) }
        end
        threads.each { |thread| thread.join }
      }
    end
  end

  context '#benchmark cpu intensive task on thread' do
    it 'return benchmark' do
      Benchmark.measure {
        read_stream, write_stream = IO.pipe
        10.times do
          Process.fork do
            write_stream.puts Fibonaci.new.fib(35)
          end
        end
        Process.waitall
        write_stream.close
        results = read_stream.read
        read_stream.close
      }
    end
  end
end