Tracking allocated objects

0.sh

echo Josh | ruby -r ./tracer.rb -e '
class User
  def initialize(id, name)
    @id, @name = id, name
  end

  def to_s
    "User #@id: #@name"
  end
end

User.new 123, gets.chomp
omg
'

tracer.rb

require 'objspace'
ObjectSpace.trace_object_allocations_start

def omg
  o = ObjectSpace
  all = o.each_object.to_a
  all.delete all
  pp all
    .select { o.allocation_class_path _1 } # ignore things we didn't see get allocated
    .select { o.allocation_method_id _1 }
    .group_by(&:class)
    .sort_by { _2.size }.to_h
    .transform_values { |objs|
      objs
        .map { "#{o.allocation_class_path _1}##{o.allocation_method_id _1}" }
        .tally
        .sort_by { _2 }
        .to_h
    }
end