Each time a standard/advanced agent wakes up to run based on a schedule it will be coupled to a requestor for the sake of this conversation a thread. I will then within that thread process all records expected in that wake up interval typically up to the maxrecords value specified. Then it goes back to sleep and does the process all over again.
Below explanation provides the running of the Agents irrespective of Agent type.
Once PegaRULES has been started and the agent activities have been enabled, the activity tasks must be run at their stated intervals.
Each agent activity started by the Master Agent is run in its own separate thread for processing, but when the agent wakes up, it queues the activity in a batch requestor that runs in a thread pool (of size specified in prconfig.xml threadpoolsize) from which these threads are obtained. This means that no more than the number of threadpoolsize agent activities will run concurrently, irrespective of the wakeup intervals on the queue.
Some agents (such as external lookup agents) may take more time to run their task (15 to 20 seconds) than other agents (.1 second). Threads for these different queues run concurrently.