In case of a concurrent trigger having max execution thread - 5, capacity level - 10, refill level - 4; if suppose we have some 100 documents piled up in the queue, will the trigger be able to pick the messages in the same order in which they have got into the queue [or order in which they were published] ?
Does a queue here means all processing will follow FIFO rule?
The title of the thread should be “Concurrent processing in Integration Server”
If an IS trigger is configured for concurrent processing, with the settings you mention, the messages will be picked up in the queue in order–but IS will process them concurrently, meaning order is destroyed.
If you need to retain order (which is maintained ONLY for events published from the same publisher) then configure the trigger for serial processing.