Hello RedBeat: A New Celery Beat Scheduler

Summary

Heroku Connect relied on Celery Beat to trigger frequent periodic tasks while synchronizing Salesforce and Heroku Postgres data, but the default file-based scheduler developed intermittent pauses and hangs that required manual intervention. Existing SQL-backed scheduling introduced blocked transactions and pauses from periodically saving and reloading the full schedule, while an existing Redis-backed package retained similar reload behavior. RedBeat moves the active schedule and runtime metadata into Redis, allowing updates through Redis keys that Beat reads on its next tick without pausing or reloading. It also uses a lock to prevent concurrent Beat daemons, supports schedule updates from other languages, and has run in production for more than a year without recurring scheduler-related incidents.

Takeaways

1. 1

   RedBeat updates the active schedule in Redis, so Celery Beat can pick up changes on its next tick without pausing and reloading the full schedule.

2. 2

   A Redis-backed schedule avoids sharing a filesystem across machines for task metadata and provides a steady, predictable Redis load instead of database load spikes during startup and shutdown.

3. 3

   RedBeat includes a lock that prevents multiple scheduler daemons from running concurrently, addressing an issue that can occur during scaling or development.