We have created a script to send threshold and polling notification to a OVO management server.  When multiple events are triggered at the same time I'm finding that not all of the events are being processed. Are parameters in em.properties are limiting the number of scripts that can run at once in parallel.  

em.notification.notification_max_pool_size=20
em.notification.notification_max_task_size=5000
em.notification.script_notification_handler_pool_size=1
em.notification.notification_pool_size=10
em.notification.script_notification_handler_max_pool_size=1
em.notification.trap.eventmanager_trap_use_new_format=false
em.notification.script_notification_handler_queue_size=5000
em.notification.handler_max_pool_size=20
em.notification.handler_max_task_size=5000
em.notification.handler_pool_size=5
em.notification.script_notification_execution_time=300

CAPM 3.x

You can execute scripts in parallel but they may get out of order.  In order to execute scripts in parallel, update the script_notification_handler_pool_size to 10 and script_notification_handler_max_pool_size to 20 in 

/opt/CA/PerformanceCenter/EM/webapps/EventManager/WEB-INF/em.properties, then you will need to restart the event manager service.  You can also increase the queue size to something greater than 5000 if you see some script events getting dropped 

Update the queue size only if you can actually see in the EMService.log that script events are getting dropped.  For example, you should be able to see an error like "Script Notification Queue overflow". If you do not see the above error, than  increasing queue size will not help.  An event also gets generated to indicate when the queue over flows and when event processing restarts 

Queue size is limited by memory.  By default it is set to 5000 but you should be able to increase it to much higher value if you do not see any decrease in CAPC performance