This topic explains why an instance performs a dry run.
Key concept
A dry-run instance is marked as successful (normally scheduled), but has an empty runtime log, shows no execution duration, and processes no data.
Why does an instance perform a dry run?
Scenario 1: Dry run for weekly/monthly cycle
If a node is scheduled to run on Days of the Week or Day of the Month, it only processes data on the scheduled day. On all other days, the system generates a dry-run instance that does not actually execute the task. The status of this instance is Dry Run for Weekly/Monthly Cycle.
To ensure a scheduled instance processes data, set its scheduled time to at least 10 minutes after the node is deployed. Alternatively, you can backfill data using the previous day's business date, and the scheduled instance will run normally the following day.
To prevent a dry run when backfilling data for a weekly or monthly node, check the scheduled time and business date of the current day's scheduled instance. For example, if a monthly node is scheduled to run on the 1st of each month, you must set the business date to the end of the month for the data backfill. The same logic applies to weekly nodes. You can view these details by navigating to Operation Center > Scheduled Task O&M > Scheduled Instances, selecting the target instance, and viewing the corresponding fields in the Properties panel.
Scenario 2: Deprecated real-time generated instance
When you use the Immediately After Deployment option to generate a scheduled instance, only instances scheduled to run more than 10 minutes after deployment will process data. Instances scheduled to run within 10 minutes of deployment are created as dry-run instances and do not process data. The status of such an instance is Deprecated Real-Time Generated Instance.
Note For more information, see Generate an instance immediately after you deploy a node.
Scenario 3: Instance set as successful
When an instance has failed, if you trigger Set as Successful, the instance is marked as successful without actually processing data, and it does not block downstream task execution. The status of this instance is Instance Set as Successful.
Scenario 4: Instance property is set to dry run
Check whether the time property of the node is set to Dry-run on the schedule settings page in Data Studio. The status of this instance is Property Is Dry Run.
Scenario 5: Unselected instance in temporary workflow
When you backfill data, suppose node C depends on node B, and node B depends on node A. If you select only nodes A and C for the data backfill, the instance of node B performs a dry run. The status of this instance is Unselected Instance in Temporary Workflow.
Troubleshooting daily node dry runs
If a daily scheduled task performs a dry run, check whether the node is configured as a dry run on the schedule settings page.
Note T+1: Data with a business date of today is processed the next day.