Add Concurrency With ConsumerSupervisor

The properties of ConsumerSupervisor

Using multiple consumers to process events one by one concurrently is a very useful technique. To make this task even easier, GenStage comes with a special supervisor called ConsumerSupervisor. It works like a consumer and can subscribe to one or more producers. It can also monitor, start and restart child processes, just like a supervisor.

What makes ConsumerSupervisor special is that when it receives a list of events from a producer, it automatically starts a process for each event and passes the event as an argument to the process. When a child process exits successfully, a new demand will be issued by ConsumerSupervisor, and the cycle repeats. This figure illustrates how child processes are started on-demand when new events are received: