Cron
InfrastructureWork triggered by the clock.
A scheduled job: nightly cleanup, hourly reindex, the weekly digest. Named after a Unix utility from the 1970s. Fails silently by default, because nobody is waiting for it.
See also Scheduled job, Background job, UTC
Overlap
InfrastructureA scheduled job starting before the last one finished.
An hourly job that takes seventy minutes will have two copies running. Whether that is harmless or catastrophic depends entirely on what the job does.
See also Cron, Scheduled job
Scheduled job
InfrastructureWork that runs because of the time, not a user.
A job triggered on a schedule. Fails in four classic ways: timezones, overlapping runs, missed runs, and growing workloads. Alert on the absence of success, not on failure.
See also Cron, Background job, UTC