About the containers - if you are not running them in privileged mode, you should be pretty secured, especially by limiting what kind of binaries the containers have.
It is not similarly easy to do that with a lightweight hypervisor.
Agreed. I realized I inverted your hypervisor comment. Hypervisors have the compact contract that has any reasonable chance at being audited. Container security is basically a screen door.
With RabbitMQ, you ensure* that each task is only attempted by one worker at a time, and you don't have to do anything special to ensure that at the application level.
*I'm simplifying a bit, there are edge cases where e.g. you lose a worker that has already started a task but not completed it.
The use of the word "realtime" for web tends to trigger a lot of systems developers who use the term to indicate that you can predict the actual real world time that something will take to compute, typically used in automotive and robotic settings. That being said, I didn't invent the word and words have multiple meanings and contexts. In this context it simply means push-delivered data that is pushed when updated. /disclaimer
I believe "realtime" in this case pertains to the synchronization of data amongst clients through websockets. This is how I've seen the term "realtime database" most commonly used.