Are data objects slow?

data-object-with-time-parsing.rb

require 'time'
require 'virtus'
require 'benchmark/ips'

PARAMS = {
  id: "123",
  title: "Hello",
  content: "Lorem ipsum" * 100,
  created_at: Time.now.to_s,
  updated_at: Time.now.to_s
}

class ThePORO
  def initialize(id:, title:, content:, created_at:, updated_at:)
    @id = id.to_i
    @title = title
    @content = content
    @created_at = Time.parse(created_at)
    @updated_at = Time.parse(updated_at)
  end
end

class TheStruct < Struct.new(:id, :title, :content, :created_at, :updated_at)
end

class TheVirtus
  include Virtus.model

  attribute :id, Integer
  attribute :title, String
  attribute :content, String
  attribute :created_at, Time
  attribute :updated_at, Time
end

Benchmark.ips do |x|
  x.report "Dup and update" do
    params = PARAMS.clone
    params[:id] = PARAMS[:id].to_i
    params[:created_at] = Time.parse PARAMS[:created_at]
    params[:updated_at] = Time.parse PARAMS[:updated_at]
  end

  x.report "PORO" do
    ThePORO.new(
      id: PARAMS.fetch(:id),
      title: PARAMS.fetch(:title),
      content: PARAMS.fetch(:content),
      created_at: PARAMS.fetch(:created_at),
      updated_at: PARAMS.fetch(:updated_at),
    )
  end

  x.report "Struct" do
    TheStruct.new(
      PARAMS.fetch(:id).to_i,
      PARAMS.fetch(:title),
      PARAMS.fetch(:content),
      Time.parse(PARAMS.fetch(:created_at)),
      Time.parse(PARAMS.fetch(:updated_at))
    )
  end

  x.report "Virtus" do
    TheVirtus.new(PARAMS)
  end
end

data-object-without-time-parsing.rb

require 'time'
require 'virtus'
require 'benchmark/ips'

PARAMS = {
  id: "123",
  title: "Hello",
  content: "Lorem ipsum" * 100,
  created_at: Time.now,
  updated_at: Time.now,
}

class ThePORO
  def initialize(id:, title:, content:, created_at:, updated_at:)
    @id = id.to_i
    @title = title
    @content = content
    @created_at = created_at
    @updated_at = updated_at
  end
end

class TheStruct < Struct.new(:id, :title, :content, :created_at, :updated_at)
end

class TheVirtus
  include Virtus.model

  attribute :id, Integer
  attribute :title, String
  attribute :content, String
  attribute :created_at, Time
  attribute :updated_at, Time
end

Benchmark.ips do |x|
  x.report "Dup and update" do
    params = PARAMS.clone
    params[:id] = PARAMS[:id].to_i
    params[:created_at] = PARAMS[:created_at]
    params[:updated_at] = PARAMS[:updated_at]
  end

  x.report "PORO" do
    ThePORO.new(
      id: PARAMS.fetch(:id),
      title: PARAMS.fetch(:title),
      content: PARAMS.fetch(:content),
      created_at: PARAMS.fetch(:created_at),
      updated_at: PARAMS.fetch(:updated_at),
    )
  end

  x.report "Struct" do
    TheStruct.new(
      PARAMS.fetch(:id).to_i,
      PARAMS.fetch(:title),
      PARAMS.fetch(:content),
      PARAMS.fetch(:created_at),
      PARAMS.fetch(:updated_at)
    )
  end

  x.report "Virtus" do
    TheVirtus.new(PARAMS)
  end
end

results.md

Are Data Objects Slow

TL;DR

Virtus is 20+ times slower to instantiate an object from a hash than using a Plain Old Ruby Object or Struct.

If this process involves parsing timestamps into Time objects Virtus is then only 2 times slower.

We are talking 0.00001 ms vs 0.000005 ms to instantiate an object here. In the context of handling an http request in a rails app, I believe that the performance impact is non existent.

Results

With time parsing

Calculating ------------------------------------- Dup and update 1.728k i/100ms PORO 1.695k i/100ms Struct 1.760k i/100ms Virtus 928.000 i/100ms

  Dup and update     18.171k (±15.5%) i/s -     89.856k
            PORO     17.772k (±12.4%) i/s -     88.140k
          Struct     18.479k (±13.8%) i/s -     91.520k
          Virtus      9.254k (±11.5%) i/s -     46.400k

No time parsing

Calculating ------------------------------------- Dup and update 44.825k i/100ms PORO 36.665k i/100ms Struct 72.831k i/100ms Virtus 2.596k i/100ms

  Dup and update    686.871k (±15.7%) i/s -      3.362M
            PORO    427.578k (±26.1%) i/s -      1.980M
          Struct      1.222M (±20.2%) i/s -      5.826M
          Virtus     20.415k (±26.8%) i/s -     90.860k