When creating a data source (queue) in Back4, or any time later, you can set a specific execution priority for such queue.

The default priority for all new queues is -1, that means that the priority for that queue is inherited from the linked data template and it will be the same for all queues that share the same template, and have -1 in the Task priority field:

You can set the priority from 0 to 32767.

The queues with higher priority are executed before other queues, except when the number of threads is enough for all active queues to run in parallel.

The queues that are stopped (disabled) do non compete for execution.