Managing when jobs and workflows execute.

Strait provides several mechanisms to control the timing of job and workflow executions, from recurring cron schedules to delayed one-off runs.

Cron Scheduling

Jobs and workflows can be configured with a cron expression for automatic, recurring execution.

• Syntax: Standard 5-field cron syntax (e.g., 0 * * * * for every hour).
• Timezone Support: Schedules can be pinned to a specific timezone (e.g., America/Los_Angeles) via the timezone (for jobs) or cron_timezone (for workflows) fields.
• Implementation: Handled by the CronScheduler using the robfig/cron/v3 library.

Delayed Execution

Runs can be scheduled to execute at a specific point in the future.

• Mechanism: When a run is triggered with a scheduled_at timestamp in the future, it is created with a delayed status.
• Delayed Poller: A background component periodically checks for delayed runs whose scheduled_at time has passed and transitions them to queued.

Stale Run Reaper

To ensure system reliability, the Reaper background component monitors for runs that have become "stale."

• Heartbeat Monitoring: Executing runs are expected to send periodic heartbeats. If a run's heartbeat_at timestamp exceeds a configurable threshold, the reaper identifies it as stale.
• Stale Dequeued Runs: Runs that were claimed (dequeued) but never transitioned to executing are also reaped.
• Actions: Stale runs may be transitioned to crashed or system_failed, allowing them to be retried if attempts remain.

Retention Policies

The RetentionWorker manages the cleanup of old run data to prevent database bloat.

• Short Retention (30 days): Applied to terminal runs in completed, failed, canceled, or expired states.
• Long Retention (90 days): Applied to terminal runs in timed_out, crashed, or system_failed states, providing a longer window for debugging critical failures.

Execution Windows

Jobs can define an execution_window_cron. This restricts the job from being dequeued unless the current time matches the provided cron-like expression.

Skip-if-Running (Workflows)

Workflows support a skip_if_running flag. If enabled, the scheduler will skip triggering a new run if an instance of that workflow is already in a running or paused state. This is useful for preventing overlapping executions of long-running maintenance tasks.