blockingQueues | goroutine safe queues , useful as resource pools

I have a couple of infinite Flowables (getting data from BlockingQueues). I merge them and subscribe with my custom subscriber. I don't understand why I get messages only from a single input Flowable.

Here is my code:

I am still learning about java and need a recommendation on best practices.

Here is the scenerio:

1. An encrypted file comes in
2. A java app picks up the file when it comes.
3. The java app from the class that listens for the file, in its main method creates 5 blockingqueues (for the consumers), starts up a producer and 5 consumer threads.
4. The producer thread reads the file and creates 1 big object consisting of 5 other smaller objects within it.
5. The producer thread then puts each big object into the blockingqueues.
6. Each consumer thread looks into its own blockingqueue, retrieves the big object, then it retrieves 1 of the 5 smaller objects and writes a file with the information related to that 1 small object.

my problem: If anything goes wrong in the producer thread while its reading the file, I want the listening class (the one that starts everything up) to know about it so that it can change the extension of the encrypted file to .err

I also want the other 5 consumer threads to know if something wrong occurs in the producer thread so that they can also change the extension of the file that each creates to .err

Not sure if a wrapper class would be recommended more in this scenerio that I pass into the blockingqueue or to use a static variable in the listening or producer class that all the threads can look at to know if an error occurred. Thank you for your help

or if there is a better solution please let me know

I'm using Spring for the first time and am trying to implement a shared queue wherein a Kafka listener puts messages on the shared queue, and a ThreadManager that will eventually do something multithreaded with the items it takes off the shared queue. Here is my current implementation:

The Listener:

I have an java application running in a payara 5.

I need to pool some engine objects (from a library) that my beans will use. Creating the engines needs to be done in a separate thread.

Therefor I came up with my EnginePool and my EngineProducer. The idea is that the EnginePool manages two BlockingQueues. One for available engines and one for engines that were used by a bean and need to become available again. The EnginePool should be only available once so it is a singleton.

I have the following setup. There is a message distributor that spreads inbound client messages across a configured number of message queues (LinkedBlockingQueues in my case), based on an unique identifier called appId (per connected client):

im an building a multithreaded application, using WorkerThreads which process Tasks from BlockingQueues. The worker looks as follws (as an abstract class. subclasses implement processItem()).