Job priorities and queues in Ruby on Rails - Mini Project: Build & Apply

Job priorities and queues

📖 Scenario: You are building a simple background job system in a Rails app. Jobs have different priorities and are placed in different queues based on their priority.This helps the app process urgent tasks faster and less urgent tasks later.

🎯 Goal: Create a basic job class with priority levels and assign jobs to queues accordingly.Learn how to set up job priorities and queues in Rails Active Job.

📋 What You'll Learn

Create a job class with a priority attribute

Define queues for high, medium, and low priority jobs

Assign jobs to the correct queue based on priority

Enqueue jobs with different priorities

💡 Why This Matters

🌍 Real World

Many web apps use background jobs to handle tasks like sending emails or processing data. Prioritizing jobs helps important tasks run faster.

💼 Career

Understanding job priorities and queues is essential for backend developers working with Rails and background processing frameworks like Sidekiq or Delayed Job.

1

Create a job class with a priority attribute

Create a Rails job class called PriorityJob that inherits from ApplicationJob. Add an attr_accessor for priority.

Ruby on Rails

class PriorityJob < ApplicationJob
  # Your code here
end

Need a hint?

Use attr_accessor :priority inside the job class to add a priority attribute.

2

Define queues for high, medium, and low priority jobs

Inside the PriorityJob class, define three queues named high_priority, medium_priority, and low_priority using queue_as method. Use a method queue_name that returns the queue name based on the priority value: 'high' maps to :high_priority, 'medium' to :medium_priority, and 'low' to :low_priority. Then set queue_as :queue_name dynamically.

Ruby on Rails

class PriorityJob < ApplicationJob
  attr_accessor :priority

  # Your code here to define queues and queue_name method
end

Need a hint?

Use a case statement inside queue_name to return the correct queue symbol.

Use queue_as :queue_name to set the queue dynamically.

3

Assign jobs to the correct queue based on priority

Add an initialize method to PriorityJob that accepts a priority argument and sets the priority attribute. This will ensure each job instance knows its priority and queue.

Ruby on Rails

class PriorityJob < ApplicationJob
  attr_accessor :priority

  def initialize(priority)
    # Your code here to set priority
  end

  def queue_name
    case priority
    when 'high' then :high_priority
    when 'medium' then :medium_priority
    else :low_priority
    end
  end

  queue_as :queue_name
end

Need a hint?

Define initialize(priority) and set @priority = priority.

4

Enqueue jobs with different priorities

In your Rails app, enqueue three PriorityJob jobs with priorities 'high', 'medium', and 'low' using PriorityJob.new(priority).enqueue or perform_later if preferred. This will place each job in the correct queue.

Ruby on Rails

class PriorityJob < ApplicationJob
  attr_accessor :priority

  def initialize(priority)
    @priority = priority
  end

  def queue_name
    case priority
    when 'high' then :high_priority
    when 'medium' then :medium_priority
    else :low_priority
    end
  end

  queue_as :queue_name
end

# Your code here to enqueue jobs with different priorities

Need a hint?

Call PriorityJob.perform_later('high') and similarly for 'medium' and 'low'.