1. A system for processing work items in a workflow, the system comprising: a plurality of queues each comprising a plurality of work items; and a processor to: determine a retrieval priority for each of the plurality of queues; retrieve at least one work item from each of the plurality of queues according to the retrieval priority; store the at least one work item retrieved from each of the plurality of queues in a workflow data structure; and selectively adjust an amount of processing capacity to process the work items stored in the workflow data structure.