Exq is a job processing library compatible with Resque / Sidekiq for the Elixir language.

Exq uses Redis as a store for background processing jobs. It is especially useful for integrating with Ruby / Rails projects that already use Resque / Sidekiq for background jobs.

This assumes you have an instance of Redis to use.

Add exq to your mix.exs deps (replace version with the latest hex.pm package version):

  defp deps do
    [
      # ... other deps
      {:exq, "~> 0.1.4"}
    ]
  end

Then run mix deps.get.

By default, Exq will use configuration from your config.exs file. You can use this to configure your Redis host, port, password, as well as namespace (which helps isolate the data in Redis). The "concurrency" setting will let you configure the amount of concurrent workers that will be allowed, or :infinite to disable any throttling.

config :exq,
  host: '127.0.0.1',
  port: 6379,
  password: "optional_redis_auth",
  namespace: "exq",
  concurrency: :infinite,
  queues: ["default"]

Exq supports concurrency setting per queue. You can specify the same concurrency option to apply to each queue or specify it based on a per queue basis.

Concurrency for each queue will be set at 1000:

config :exq,
  host: '127.0.0.1',
  port: 6379,
  namespace: "exq",
  concurrency: 1000,
  queues: ["default"]

Concurrency for q1 is set at 10_000 while q2 is set at 10:

config :exq,
  host: '127.0.0.1',
  port: 6379,
  namespace: "exq",
  queues: [{"q1", 10_000}, {"q2", 10}]

You can add Exq into your OTP application list, and it will start an instance of Exq along with your application startup. It will use the configuration from your config.exs file.

  def application do
    [
      applications: [:logger, :exq],
      #other stuff...
    ]
  end

When using Exq through OTP, it will register a process under the name :exq - you can use this atom where expecting a process name in the Exq module.

You can also start Exq manually and set configuration per instance.

Here is an example of how to start Exq manually:

{:ok, sup} = Exq.start_link

To connect with custom configuration options (if you need multiple instances of Exq for example), you can pass in options under start_link:

{:ok, sup} = Exq.start_link([host: '127.0.0.1', port: 6379, namespace: 'x'])

By default, Exq will register itself under the :exq atom. You can change this by passing in a name parameter:

{:ok, exq} = Exq.start_link(name: :exq_custom)

You can run Exq standalone from the command line, to run it:

> mix exq.run

To enqueue jobs:

{:ok, ack} = Exq.enqueue(:exq, "default", "MyWorker", ["arg1", "arg2"])

{:ok, ack} = Exq.enqueue(:exq, "default", "MyWorker/custom_method", [])

You can also enqueue jobs without starting workers:

{:ok, sup} = Exq.Enqueuer.start_link([port: 6379])

{:ok, ack} = Exq.Enqueuer.enqueue(:exq_enqueuer, "default", "MyWorker", [])

To create a worker, create an elixir module matching the worker name that will be enqueued. To process a job with "MyWorker", create a MyWorker module. Note that the perform also needs to match the number of arguments as well.

Here is an example of a worker:

defmodule MyWorker do
  def perform do
    # will get called if no custom method passed in
  end
end

We could enqueue a job to this worker:

{:ok, jid} = Exq.enqueue(:exq, "default", "MyWorker", [])

By default, the perform method will be called. However, you can pass a method such as MyWorker/custom_method

Example Worker:

defmodule MyWorker do
  def custom_method(arg1) do
    # will get called since job has  "/custom_method" postfix
    # Not that arity must match args
  end
end

Which can be enqueued by:

{:ok, jid} = Exq.enqueue(exq, "default", "MyWorker/custom_method", [])

Exq comes with a Web UI to monitor your workers:

To start the web UI:

> mix exq.ui

You can also use Plug to connect the web UI to your Web application.

Contributions are welcome. Make sure to run mix test --no-start to ensure your changes have not caused any regressions.

Justin McNally (j-mcnally) (structtv)

Mike Lawlor (disbelief)

Udo Kramer (optikfluffel)

Roman Smirnov (romul)

Rob Gilson (D1plo1d)

Benjamin Tan Wei Hao (benjamintanweihao)