Producer and consumer pipelines with back-pressure for Elixir




GenStage is a specification for exchanging events between producers and consumers.

This project currently provides the following functionality:

  • GenStage (docs) - a behaviour for implementing producer and consumer stages

  • ConsumerSupervisor (docs) - a supervisor designed for consuming events from GenStage and starting a child process per event

You may also be interested in the Flow project for building computational flows using regular map, reduce and more that run in parallel on top of GenStage. See documentation for Flow or José Valim's keynote at ElixirConf 2016 introducing the main concepts behind GenStage and Flow.


Examples for using GenStage and ConsumerSupervisor can be found examples directory:

  • ProducerConsumer - a simple example of setting up a pipeline of A -> B -> C stages and having events flowing through

  • ConsumerSupervisor - an example of how to use one or more ConsumerSupervisor as a consumer to a producer that works as a counter

  • GenEvent - an example of how to use GenStage to implement a GenEvent replacement that leverages concurrency and provides more flexibility regarding buffer size and back-pressure

  • RateLimiter - an example of performing rate limiting in a GenStage pipeline


GenStage requires Elixir v1.5. Just add :gen_stage to your list of dependencies in mix.exs:

def deps do
  [{:gen_stage, "~> 0.14"}]


Same as Elixir.