Tip: Automatic Broadcast Expiry

Cylc Tips
1

Broadcasts automatically expire (i.e, are deleted) once they are no longer required by upcoming tasks.

This means that if you try to re-run a task from the previous cycle, its broadcasts will likely have been expired. In Cylc 8.6.0, we have pushed back the broadcast expiry limit to make it easier to re-run tasks from the previous cycle. For more information, see the user guide.

Another consequence of broadcast expiry is that broadcasts made to historical cycles (behind the broadcast expiry point) will expire instantly. The cylc trigger --on-resume option was added to allow us to broadcast to a cycle before triggering the task:

  • Pause the workflow.
  • Trigger the task using the --on-resume option (the task will not run until the workflow is resumed).
  • Issue the broadcast.
  • Resume the workflow (the task will now run).

At Cylc 8.6.0, automatic broadcast expiry is suspended while the workflow is paused which simplifies this process:

  • Pause the workflow.
  • Issue the broadcast.
  • Trigger the task (no special option required).
  • Resume the workflow.

Note the order of the broadcast and trigger operations has swapped to the logical order.

The --on-resume option has been removed.