We are using EJB3 in our application and we've created an interceptor to check whether the user has already sent a request or not. if we noticed that the user has already sent a request then in this interceptor we need to suspend that thread and wait till the former request being completed otherwise the thread will proceed.
in order to find whether or not a user has sent a request, each time a request comes, we store its user id in a Map structure.
here is the body of the our interceptor
now, I am skeptical on the way this works. I just created this interceptor based on information gathering through the internet and not sure that works fine. Unfortunately, I can't create a situation in which we can test the system.