Understand Consumer Demand

Consumer demand

We previously saw that PageProducer was asked for 1,000 events. We may wonder where the number comes from. By default, stages of the :consumer and :producer_consumer type ensure that the demand for new events is between 500 and 1,000. We can configure this through the min_demand and max_demand settings. When a consumer subscribes to a producer in the init/1 function, we pass a tuple with some configuration options:

#`subscribe_to` options can be a list of tuples.
sub_opts = [{PageProducer, min_demand: 500, max_demand: 1000}]
{:consumer, initial_state, subscribe_to: sub_opts}