How to Schedule Jobs in Rails: Simple Guide with Examples

In Rails, you schedule jobs by creating an ActiveJob class and then using a scheduler like sidekiq-scheduler or whenever gem to run it at set times. You define the job's work in the job class and configure the scheduler to trigger it automatically.

Syntax

To schedule a job in Rails, you first create a job class inheriting from ApplicationJob. Then you use a scheduler gem or system cron to run the job at specific times.

• class MyJob < ApplicationJob: Defines the job class.
• perform method: Contains the code to run.
• Scheduler config: Defines when the job runs (e.g., every hour).

ruby

class MyJob < ApplicationJob
  queue_as :default

  def perform(*args)
    # Your task code here
    puts "Job is running"
  end
end

Example

This example shows how to create a simple job and schedule it to run every minute using the sidekiq-scheduler gem.

ruby

# app/jobs/print_time_job.rb
class PrintTimeJob < ApplicationJob
  queue_as :default

  def perform
    puts "Current time: #{Time.now}"
  end
end

# config/sidekiq.yml
:schedule:
  print_time_job:
    cron: "* * * * *"  # runs every minute
    class: "PrintTimeJob"

# Run Sidekiq with scheduler enabled:
# bundle exec sidekiq -C config/sidekiq.yml

Output

Current time: 2024-06-01 12:00:00 +0000
Current time: 2024-06-01 12:01:00 +0000
... (runs every minute)

Common Pitfalls

• Not setting up a background job processor like Sidekiq or Delayed Job, so scheduled jobs never run.
• Forgetting to configure the scheduler (cron or sidekiq-scheduler) properly.
• Running jobs synchronously in development without a queue, causing delays.
• Not setting the correct queue name or environment for the job.

ruby

# Wrong: Calling job perform method directly (runs immediately, no scheduling)
PrintTimeJob.new.perform

# Right: Enqueue job to run asynchronously
PrintTimeJob.perform_later

Quick Reference

Summary tips for scheduling jobs in Rails:

• Create job classes inheriting from ApplicationJob.
• Use perform_later to enqueue jobs asynchronously.
• Choose a background processor like Sidekiq or Delayed Job.
• Use scheduler gems like sidekiq-scheduler or whenever for timing.
• Test jobs in development with perform_now if needed.

Key Takeaways

Create jobs by subclassing ApplicationJob and defining a perform method.

Use perform_later to enqueue jobs for background processing.

Configure a scheduler like sidekiq-scheduler or whenever to run jobs at set times.

Always run a background job processor (e.g., Sidekiq) to execute scheduled jobs.

Avoid calling perform directly to prevent blocking your app.