Request-scoped data

I want to have data with request scope where I can control the lifecycle. Obviously I can determine when the data is first added to the request, so I know the beginning of the lifecycle. However, how do I know when the lifecycle is over? I don't want each JSP and Servlet to have to know if it is the last user of the request in order to explicitly do end-of-life cleanup. Is there some other way I can do this?

I don't want each JSP and Servlet to have to know if it is the last user of the request

HTTP request are per user. They don't get reused. So in a servlet context the end of a request is effectively once the service() method has run.