A method for tracking the change in counts of objects in ObjectSpace

object_count_change.shard.rb

module Kernel
  def object_count_change(root = ActiveRecord::Base)
    before = Hash.new(0).tap { |hash| ObjectSpace.each_object(root) { |obj| hash[obj.class.to_s] += 1 } }
    yield
    after  = Hash.new(0).tap { |hash| ObjectSpace.each_object(root) { |obj| hash[obj.class.to_s] += 1 } }
  
    Hash.new.tap do |change|
      all_keys = (before.keys + after.keys).uniq.sort
      all_keys.each { |key| change[key] = after[key] - before[key] }
    end
  end
end