Queueing in Delayed_Job with ActiveJobs

Question

In a controller, I have a post request by an authenticated user firing an ActiveJob.

RunReportsJob.perform_later(param1, param2, param3)

It works without errors. But if the user presses the button (firing post request) again to trigger RunReportsJob while it was already running, 2 jobs happen at the same time. I setup delayed_job because I thought it was a queueing service, and would keep everything at one job at a time. But this isn't happening. Below is my configuration:

# app/jobs/run_reports_job.rb:

class RunReportsJob < ActiveJob::Base
      queue_as :RunReports
      include ShopifyApp::Controller
      # --------------------------------------------------------------
      # JOB ERROR MANAGEMENT
      # --------------------------------------------------------------
      rescue_from(ActiveRecord::RecordNotFound) do |exception|
           # Do something with the exception
           logger.debug "Hit rescue_from"
      end
      # --------------------------------------------------------------
      # JOB FUNCTION
      # --------------------------------------------------------------
      def perform(param1, param2, param3)
        # some code is performed here
      end
 end

# config/application.rb:

config.active_job.queue_adapter = :delayed_job

# config/initializers/delayed_job_config.rb:

Delayed::Worker.max_attempts = 1
Delayed::Worker.max_run_time = 12.hours

Answer 1

You'll have to add some logic before RunReportsJob.perform_later(param1, param2, param3) to check for an already queued job priority and increase the priority number (lower number is higher priority according to documentation) in this example the queue:

highest_priority = Delayed::Job.where(queue: :RunReports).maximum(:priority)
Delayed::Worker.default_priority = highest_priority + 1 if highest_priority

RunReportsJob.perform_later(param1, param2, param3)

DelayedJob uses a table to save all the jobs info check the documentation at https://github.com/collectiveidea/delayed_job#gory-details