1Solid Queue is a DB-based queuing backend for Active Job, designed with 2simplicity and performance in mind. 3 4Besides regular job enqueuing and processing, Solid Queue supports delayed jobs, 5concurrency controls, recurring jobs, pausing queues, numeric priorities per 6job, priorities by queue order, and bulk enqueuing (enqueue_all for Active Job's 7perform_all_later). 8 9Solid Queue can be used with SQL databases such as MySQL, PostgreSQL or SQLite, 10and it leverages the FOR UPDATE SKIP LOCKED clause, if available, to avoid 11blocking and waiting on locks when polling jobs. It relies on Active Job for 12retries, discarding, error handling, serialization, or delays, and it's 13compatible with Ruby on Rails's multi-threading. 14