Rails Background Job Patterns Skill

Rails Background Job Patterns

Analyze and recommend patterns for reliable, efficient background jobs in Rails applications.

Follow standard Rails conventions for retry_on, discard_on, queue_as, and basic ActiveJob structure. Focus on the opinionated patterns below.

Quick Reference

| Pattern | Use When | |---------|----------| | _later/_now convention | Every async operation — name both versions | | Shallow job + model logic | All new jobs — jobs are wrappers only | | Double-check locking | Idempotency with concurrent workers | | Self-splitting batch | Datasets too large for one job | | limits_concurrency | Solid Queue race condition prevention | | perform_all_later | Bulk enqueueing (Rails 7.1+) |

Supporting Documentation

patterns.md - Complete job patterns with detailed examples

Core Principles

Jobs are shallow wrappers: Business logic lives in models (omakase) or service objects (service-oriented). Jobs handle only queuing and retry infrastructure
_later/_now convention: Define thing_later (queues job) and thing (does work) on the model. The job just calls the model method
Double-check locking for idempotency: Guard clause THEN with_lock THEN guard again — prevents races between concurrent workers
Pass IDs, not objects: Avoid serialization issues and stale data
Queue segmentation: Separate critical, default, low, and mailers

The `_later`/`_now` Pattern (37signals)

# Model defines both versions
class Webhook::Delivery < ApplicationRecord
  after_create_commit :deliver_later

  def deliver_later
    Webhook::DeliveryJob.perform_later(self)
  end

  def deliver
    in_progress!
    self.response = perform_request
    completed!
  rescue => e
    failed!(e.message)
  end
end

# Job is a shallow wrapper — no business logic
class Webhook::DeliveryJob < ApplicationJob
  queue_as :webhooks
  def perform(delivery)
    delivery.deliver
  end
end

Idempotency: Double-Check Locking

The critical pattern — guard clause alone has a race window. Always combine with with_lock:

def perform(import_id)
  import = Import.find(import_id)
  return if import.completed?          # Fast path: skip lock if done

  import.with_lock do
    return if import.completed?        # Safe path: re-check under lock
    process_import(import)
    import.update!(status: "completed")
  end
end

Self-Splitting Batch Jobs

For datasets too large for one job — the job re-enqueues itself for the next chunk:

class LargeImportJob < ApplicationJob
  BATCH_SIZE = 1_000

  def perform(dataset_id, offset = 0)
    records = Dataset.find(dataset_id).records.offset(offset).limit(BATCH_SIZE)
    return if records.empty?

    process_batch(records)
    self.class.perform_later(dataset_id, offset + BATCH_SIZE)
  end
end

Concurrency Control

Solid Queue — `limits_concurrency`

class Storage::MaterializeJob < ApplicationJob
  queue_as :backend
  limits_concurrency to: 1, key: ->(owner) { owner }

  def perform(owner)
    owner.materialize_storage
  end
end

Sidekiq — `sidekiq-unique-jobs`

class SyncUserJob < ApplicationJob
  sidekiq_options lock: :until_executed,
                  lock_args_method: ->(args) { [args.first] }

  def perform(user_id)
    UserSyncService.new(user_id).sync!
  end
end

Lock types: :until_executing (unique in queue), :until_executed (through completion), :until_and_while_executing (most restrictive).

Bulk Enqueueing (Rails 7.1+)

class Notification::Bundle
  def self.deliver_all_later
    due.find_in_batches do |batch|
      jobs = batch.map { |bundle| DeliverJob.new(bundle) }
      ActiveJob.perform_all_later(jobs)  # Single DB operation
    end
  end
end

Multi-Tenant Context Serialization

For apps using CurrentAttributes with multi-tenancy — automatically serialize account context across job execution. See patterns.md for the FizzyActiveJobExtensions pattern that captures Current.account on enqueue and restores it on perform.

Skip this pattern for single-tenant apps.

Anti-Patterns

| Anti-Pattern | Fix | |-------------|-----| | Business logic inside job | Omakase: delegate to model. Service-oriented: delegate to service | | Guard clause without with_lock | Use double-check locking pattern above | | find_in_batches all in one job | Self-splitting batch or perform_all_later | | No queue segmentation | Use priority queues (critical/default/low/mailers) |

Context Detection

| Check | Command | Implication | |-------|---------|-------------| | Job adapter | grep "queue_adapter" config/ | Solid Queue vs Sidekiq patterns | | Multi-tenancy | grep "Current.account" app/ | Context serialization needed | | Rails version | grep "rails " Gemfile.lock | perform_all_later available 7.1+ | | Recurring jobs | Check config/recurring.yml or sidekiq_schedule.yml | Respect existing scheduler |

Output Format

When analyzing or creating jobs, provide:

Job file in app/jobs/ with retry/discard configuration
Idempotency strategy (double-check locking, unique constraint)
Queue assignment with rationale
Test outline using ActiveJob::TestHelper
Monitoring notes (logging, metrics, alerting)

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