Avoid Dropping Events in Listen Processors for Full Queues

Multiple listening Processors, including ListenSyslog and ListenTCP, depend on the nifi-event-transport module and the NettyEventServer to receiving incoming messages. These components use the ByteArrayMessageChannelHandler to add parsed messages to a configured queue for subsequent processing when the framework triggers the Processor.

ListenSyslog and ListenTCP use a LinkedBlockingQueue with a configurable maximum size as an internal buffer, and LinkedBlockingQueue.add() throws an IllegalStateException if the caller attempts to add an element that exceeds the maximum queue size. As a result of this approach, these Processors can drop messages when the maximum queue size is too low.

The supporting ByteArrayMessageChannelHandler should be improved to call a method other than LinkedBlockingQueue.add() to avoid dropping messages while waiting for the Processor to handle queued events.