Spining multiple PageConsumer using the book provided code, raise an error
children = [ PageProducer, Supervisor.child_spec(PageConsumer, id: :consumer_a), Supervisor.child_spec(PageConsumer, id: :consumer_b) ] But I open an issue on Github Elixir repo, and the fix proposed by Jose Valim is
# in the consumer PageConsumer module def start_link(opts) do GenStage.start_link(__MODULE__, [], name: opts[:name]) end # application.ex children = [ {Scrapper.PageProducer, []}, Supervisor.child_spec({Scrapper.PageConsumer, [name: :consumer_a]}, id: :consumer_a), Supervisor.child_spec({Scrapper.PageConsumer, [name: :consumer_b]}, id: :consumer_b) ]