deep_memsize.rb

require "set"
require "objspace"

module DeepMemsize
  class << self
    def memsize_of(object, seen = Set.new.compare_by_identity)
      return 0 unless seen.add?(object)

      size = ObjectSpace.memsize_of(object)
      object.instance_variables.each { |v| size += memsize_of(object.instance_variable_get(v), seen) }

      case object
      when Hash
        object.each { |k, v| size += memsize_of(k, seen) + memsize_of(v, seen) }
      when Array
        object.each { |i| size += memsize_of(i, seen) }
      end
      size
    end
  end
end