Introduction

Goal

In this tutorial, we will introduce you to Background Jobs in Rails. It aims to teach you how to improve your Rails application's performance by handling long-running tasks asynchronously.

Learning Objectives

By the end of this tutorial, you'll understand:
- What background jobs are and why you need them
- How to create and run background jobs in Rails
- How to use Active Job and Sidekiq gems for background processing

Prerequisites

You should have a basic understanding of:
- Ruby programming language
- Rails framework
- ActiveRecord and MVC pattern

Step-by-Step Guide

Concept of Background Jobs

Background jobs are tasks that run behind the scenes without interfering with the user's experience on your web application. They are commonly used for tasks like sending emails, handling payments, or processing images, which can take a significant amount of time. By running these tasks asynchronously in the background, your application remains responsive to users.

Creating Background Jobs

Rails provides a built-in framework called Active Job for creating, scheduling, and executing background jobs. Active Job provides a common interface for multiple queuing backends (such as Sidekiq, Resque, or Delayed Job).

To create a job, you'll use the rails generate job command followed by the name of the job:

rails generate job process_image

This will generate a file named process_image_job.rb inside app/jobs directory.

Running Background Jobs

To run a background job, you'll call perform_later method on the job class:

ProcessImageJob.perform_later(image)

The perform_later method will add the job to the queue and the Active Job framework will execute it when it gets to the front of the line.

Code Examples

Example 1: Creating and Running a Job

Here's an example of a basic job that resizes an image:

# app/jobs/process_image_job.rb
class ProcessImageJob < ApplicationJob
  queue_as :default

  def perform(image)
    # Do image processing here
    image.resize_to_limit(600, 600)
    image.save!
  end
end

Then you can run this job from a controller like this:

# app/controllers/images_controller.rb
class ImagesController < ApplicationController
  def create
    image = Image.create!(image_params)
    ProcessImageJob.perform_later(image)
    redirect_to images_path
  end
end

Example 2: Using Sidekiq for Background Processing

You can also use Sidekiq, a popular gem for background processing in Rails:

# config/application.rb
module YourApp
  class Application < Rails::Application
    config.active_job.queue_adapter = :sidekiq
  end
end

Summary

In this tutorial, we covered the basics of background jobs in Rails. We learned why background jobs are necessary, how to create and run them, and how to use Active Job and Sidekiq for background processing.

For further learning, you can explore how to handle job failures, how to schedule jobs to run at specific times, and how to monitor your background jobs.

Practice Exercises

1. Create a background job that sends a welcome email to a user after they sign up.
2. Create a background job that collects daily statistics and sends a report email.
3. Set up Sidekiq in a Rails application and use it to process background jobs.

Remember, the key to mastering background jobs in Rails is practice. Happy coding!