refactor Remi worker

create_notifications_worker.rb

# from https://twitter.com/mercier_remi/status/1021669831190433792
class CreateNotificationsWorker
  include Sidekiq::Worker
  def perform
    users = User.all
    users.each do |user|
      tasks = user.tasks
      tasks.each do |task|
        if task.deadline && task.status == 'pending' && task.notified_user == false
          @notification = Notification.create!(user_id: user.id, task_id: task.id)
          task.notified_user = true
          task.save!
        end
      end
    end
  end
end

• Line 6 you load all user 💥
• Line 7 you load all user's task even if you need only the one that are pending, where notified_user is false or where deadline is not nil or false
• tasks.each load all task. Check .find_each if you can have many tasks.
• Line 9, if 'pending' is an enum you can instead refer to it as Task.statuses[:pending]
• Line 10, do you need the @?
• What happens if save! raise an exception?

Instead you could write (assuming task.deadline need to be not nil, and status an enum)

class CreateNotificationsWorker
  include Sidekiq::Worker
  def perform
    Task.pending.where(user: User.all, notified_user: false).where.not(deadline: nil).find_each do |task|
      Notification.create!(user_id: user.id, task_id: task.id)
      task.notified_user = true
      task.save!
    rescue ActiveRecord::RecordInvalid, ActiveRecord::RecordNotSaved => exception
      # Notify your bug library like (airbrake, honeybadger...) with the `exception`
      next
    end
  end
end

For the long query you could put into a method.

class CreateNotificationsWorker
  include Sidekiq::Worker
  def perform
    pending_tasks_to_notify.find_each do |task|
      #....
    end
  end

  private
  
  def pending_tasks_to_notify
    Task.pending.where(user: User.all, notified_user: false).where.not(deadline: nil)
  end
end

Task.pending => Great idea! I had completely forgotten about these methods associated with enums.
.where.not => Sweet!
find_each=> Sonia talked to me about it yesterday. Really cool way to reduce the load on memory.

Thanks, @benoittgt for all these ameliorations.

I don't use any bug library (not that I'm aware of anyway). Which one would you suggest I should start with?

We use airbrake an are quite happy about it. But honeybadger seems good too.