Sidekiq

Sidekiq is a simple, efficient background processing library for Ruby applications, created by Mike Perham (founder of Contributed Systems). Since its initial release in 2012, Sidekiq has become the most popular background job processor in the Ruby ecosystem, used by GitHub, Shopify, Stripe, Airbnb, and thousands of other companies to handle billions of jobs per day. Sidekiq uses Redis as its data store and message broker, enabling multi-process and multi-machine job distribution. The core design philosophy is simplicity and performance: jobs are defined as plain Ruby classes with a perform method, and enqueued by calling the perform_async class method, which serializes the job arguments as JSON and pushes them onto a Redis queue. Worker processes then pop jobs from the queue and execute them. Key features include: multiple queue support with configurable priority and weight, scheduled jobs (perform_in and perform_at for delayed execution), recurring jobs via the sidekiq-cron extension, job retries with configurable maximum attempts and exponential backoff, dead job tracking and manual retry capabilities, middleware architecture for cross-cutting concerns like logging, metrics, and database connection management, graceful shutdown with job draining (completing in-progress jobs before terminating), Web UI dashboard (sidekiq-web) for monitoring queue statistics, retry queues, dead jobs, and live metrics, connection pooling for Redis and database connections, Active Job integration for Rails applications, and batch processing via the Sidekiq Pro add-on. Sidekiq comes in three editions: Open Source (MIT), Pro (paid, adds batches, rate limiting, and stats), and Enterprise (paid, adds unique jobs, cron, leader election, and historical metrics).