in reply to Recommend an asynchronous HTTP server CPAN modules?

If each request takes "10-20 seconds to execute," you might have a need for a workflow manager or a job-queueing system for which the user-facing web site becomes a front-end. Requests are queued in some way, perhaps through a database table, and a set of "workers" process them and post results ... but the number of workers remains constant as the flow of requests ebbs and flows. As the user (or JavaScript) refreshes the user's screen, he sees his request "submitted / waiting / in process / completed." There are lots of packages of this sort in CPAN.