Locked Event Handler or Event Handler Set Processing 
You can schedule these background jobs in SAP Event Management (SAP EM) to execute the following:
Subsequent processing of event messages that arrive for an event handler at a time when SAP EM is locking it
Example
For example, somebody saves a shipment that updates an event handler, while you are simultaneously trying to send an event message to SAP EM for this event handler. SAP EM does not process this event message as the data update from the shipment is locking the event handler. In order that SAP EM processes the event message for this event handler at a later time, you have scheduled the appropriate background job correspondingly.
If you need to parallelize this subsequent processing due to a very high volume of event messages for previously locked Event Handlers, you can schedule this with an additional report /SAPTRX/PROCESS_LOCKED_EHS_PPF that creates multiple background jobs using the Parallel Processing Framework.
Assign an event handler once again to an event handler set that SAP EM is locking
Example
For example, a colleague assigns an event handler to an event handler set. In doing this, the colleague locks this set. You simultaneously try to assign another event handler to this event handler set. To ensure that, in spite of the temporary lock, SAP EM assigns your event handler to the set, you have scheduled the appropriate background job.
On the SAP Easy Access screen for Event Management , choose .
For parallel processing previously locked Event Handlers using the Parallel Processing Framework with report /SAPTRX/PROCESS_LOCKED_EHS_PPF, you can customize the number of parallel processing jobs per Application Type / Server Name and Server Group for Application Type EM_P_L_EHS (Process Event Messages for Previously Locked Event Handlers).
In SAP Customizing Implementation Guide for Event Management , choose .
Schedule report /SAPTRX/PROCESS_LOCKED_EHS_PPF (Process Event Messages for Previously Locked Event Handlers with Parallel Processing Framework) to run as a background task.