module ActiveSupport::MessagePack::Serializer

def message_pack_pool
  @message_pack_pool ||= begin
    unless message_pack_factory.frozen?
      Extensions.install(message_pack_factory)
      install_unregistered_type_handler
      message_pack_factory.freeze
    end
    message_pack_factory.pool(ENV.fetch("RAILS_MAX_THREADS", 5).to_i)
  end
end