How we made PlanetScale’s background jobs self-healing

This post details how PlanetScale made its background jobs self-healing and resilient. Key contributions include: 1. Implementing scheduler jobs that run on a cron to re-queue missed tasks if queues are lost. 2. Storing job state in the database (e.g., 'pending' state for database creation) to enable recovery. 3. Integrating Sidekiq client middleware with Flipper for feature flags to disable scheduled jobs during incidents. 4. Introducing bulk scheduling (`perform_bulk`) to improve efficiency for large numbers of jobs. 5. Adding `perform_with_jitter` to spread job execution over time and avoid overwhelming external APIs. 6. Strategies for handling job uniqueness, including exiting quickly if state is no longer valid, using database locks, and leveraging Sidekiq Enterprise's unique jobs feature.