The processing of the next external event does not start before the action closure of the current event is completely processed. That is, all internal events resulting from the processing of this current external event must be completely processed.
Also, when processing an event, external or internal, the engine does not process another event in parallel: the evaluation engine is single-threaded. When BPM Events is busy processing events and more events are loaded in the queue, be aware that it takes more time to process the events.
Note: When a rule action asynchronously activates an external system, the BPM Events engine considers the action over as soon as the call has been transferred to the external system. This call is only part of the action closure, and is usually complete before the actual external action is complete. Thus, external actions may still proceed in external systems, unknown from BPM Events, concurrently with the processing of the next event.
