===== +Delayed+ is a multi-threaded, SQL-driven ActiveJob backend used at {Betterment}[https://betterment.com] to process millions of background jobs per day. It supports *postgres*, *mysql*, and *sqlite*, and is designed to be: - *Reliable*, with co-transactional job enqueues and guaranteed, at-least-once execution - *Scalable*, with an optimized pickup query and concurrent job execution - *Resilient*, with built-in retry mechanisms, exponential backoff, and failed job preservation - *Maintainable*, with robust instrumentation, continuous monitoring, and priority-based alerting For an overview of how Betterment uses +delayed+ to build resilience into distributed systems, check out the talk ✨{Can I break this?}[https://www.youtube.com/watch?v=TuhS13rBoVY]✨ given at RailsConf 2021!