Each task has three associated times:

  • created is the time the task was created;
  • deadline is the time by which the task must be completed; and
  • expires is the time after which all record of the task and its runs will be deleted.

The deadline exists to ensure that tasks do not remain pending forever. It is usually set to one day after created, on the assumption that running the task more than a day later is not useful.

Task expiration ensures that tasks are not stored indefinitely, thereby controlling storage costs. Expiration is often set to one year after creation, but for common tasks, tasks which produce large artifacts, or tasks which are unlikely to be useful later, a much shorter expiration is appropriate.