elixir-lang/gen_stage

---

elixir-lang/gen_stage.json

{
  "createdAt": "2015-08-26T17:57:36Z",
  "defaultBranch": "main",
  "description": "Producer and consumer actors with back-pressure for Elixir",
  "fullName": "elixir-lang/gen_stage",
  "homepage": "http://hexdocs.pm/gen_stage",
  "language": "Elixir",
  "name": "gen_stage",
  "pushedAt": "2025-11-07T10:42:10Z",
  "stargazersCount": 1571,
  "topics": [],
  "updatedAt": "2025-11-20T12:10:02Z",
  "url": "https://github.com/elixir-lang/gen_stage"
}

GenStage

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 two other projects built on top of GenStage:

• Flow for building computational flows using map-reduce, partitions, windows, and more that run concurrently. See the documentation for Flow or José Valim’s keynote at ElixirConf 2016 introducing the main concepts behind GenStage and Flow

• Broadway for building concurrent and multi-stage data ingestion and data processing pipelines to consume events from Amazon SQS, RabbitMQ, and others. See Broadway’s documentation or José Valim’s introduction to Broadway

Examples

Examples for using GenStage and ConsumerSupervisor can be found in the [examples]!(examples) directory:

• [ProducerConsumer]!(examples/producer_consumer.exs) - a simple example of setting up a pipeline of A -> B -> C stages and having events flowing through it

• [ConsumerSupervisor]!(examples/consumer_supervisor.exs) - an example of how to use one or more ConsumerSupervisor as a consumer to a producer that works as a counter

• [GenEvent]!(examples/gen_event.exs) - an example of how to use GenStage to implement an alternative to GenEvent that leverages concurrency and provides more flexibility regarding buffer size and back-pressure

• [RateLimiter]!(examples/rate_limiter.exs) - an example of performing rate limiting in a GenStage pipeline

Installation

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

def deps do
  [{:gen_stage, "~> 1.0"}]
end

License

Same as Elixir under Apache License 2.0. Check NOTICE and LICENSE for more information.