Writing a java server for queueing incoming HTTP Request and processing them a little while later?
I did something similar with Scala Akka actors. Instead of HTTP Request I had unlimited number of job requests come in and get added to a queue (regular Queue). Worker Manager would manage that queue and dispatch work to worker actors whenever they are done processing previous tasks. Workers would notify Worker Manager that task is complete and it would send them a new one from the queue. So in this case there is no busy waiting or looping, everything happens on message reception. You can do the same with your HTTP Requests. Akka can be used from Scala or Java and a process I described is easier to implement than it sounds.
As a web server you could use anything really. It can be Jetty, or some Servlet Container like Tomcat, or even Spray-can. All it needs to do is to receive a request and send a message to Worker Manager. The whole system would be asynchronous and non-blocking.
I want to write an Java Server may be using Netty or anything else suggested. 
The whole purpose is that I want to queue incoming HTTP Request for a while because the systems I'm targeting are doing Super Memory and Compute intensive tasks so if they are burdened with heavy load they eventually tend to get crashed.
I want to have a queue in place that will actually allow only max upto 5 requests passed to destination at any given time and hold the rest of the requests in queue.
Can this be achieved using Netty in Java, I'm equally open for an implementation in Scala, Python or clojure.