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Schedules & Periodic Tasks

In addition to one-off workflows, Simmate supports periodic tasks (schedules). These are useful for:

  • Regularly syncing data from third-party databases.
  • Performing weekly database maintenance.
  • Running "steady-state" evolutionary searches.

Starting the Scheduler

Simmate uses a single "scheduler" process to manage all periodic tasks. You only need to run one of these for your entire project.

simmate engine start-schedules

The scheduler process will:

  1. Search through all your installed apps for a schedules.py module.
  2. Register any tasks defined in those modules.
  3. Run them at their specified intervals.

Creating a Schedule

To add a schedule to your own app, create a schedules.py file in your app directory. Simmate uses the schedule library's syntax.

# my_app/schedules.py
import schedule
from my_app.workflows import my_maintenance_workflow

# Run every day at 10:30am
schedule.every().day.at("10:30").do(my_maintenance_workflow.run)

# Run every hour
schedule.every().hour.do(my_maintenance_workflow.run)

As long as my_app is in your settings.yaml under apps, the start-schedules command will find and register these tasks.

Best Practices

  • Avoid Long-Running Tasks: The default SimmateScheduler runs tasks sequentially. If one task takes 5 hours to complete, it will block all other scheduled tasks until it finishes.
  • Use run_cloud for Heavy Lifting: If your scheduled task is computationally expensive, have the schedule call run_cloud() instead of run(). This way, the scheduler just "submits" the job to the database queue and immediately moves on to the next schedule, while a worker handles the actual computation on a different machine.