Hey!

I created a simple project using GenStage only to study more deeply how the processes comunicate with each other. Instead of using the default erlang tracer, I implemented a prettier tracer and also added some extra logging stuff, that help me understand better how the stages behave with different max_demand and min_demand configurations.

The Stages

[Stock] ----------> [Chef] ------------> [Checkout] >>>>>>>>> Checkout.Task

A example of the tracing logs

15:50.768 trace: :chef      => :stock                    {:subscribe, nil, [min_demand: 3, max_demand: 5]}
15:50.768 trace: :chef      => :stock                    {:ask, 5}
15:50.769 trace: :checkout  => :chef                     {:subscribe, nil, [min_demand: 0, max_demand: 2]}
15:50.769 trace: :checkout  => :chef                     {:ask, 2}
15:52.031 trace: :stock     => :chef                     {:snt, 5}
15:53.037 trace: :chef      => :checkout                 {:snt, 2}
15:53.038 trace: :chef      => :stock                    {:ask, 2}
15:53.039 trace: :checkout  => {:task, #PID<0.255.0>}    :acai1029
15:53.039 trace: :checkout  => {:task, #PID<0.256.0>}    :acai1093
15:53.543 trace: :stock     => :chef                     {:snt, 2}
15:54.039 trace: :checkout  => :chef                     {:ask, 1}
...

Repository: https://github.com/HugoLnx/acai-restaurant

Hope it help.

PS.: I created a few issues with some ideas.