How do clients(web browser) close a python CGI program that is not responding?

[Sullivan WxPyQtKinter]

Actually my project is converting certain specially costomized  XML
file to HTML to display and edit. Sometimes the XML file is too big, or
the client upload a very huge file for the server to process, which
exceeds the processing ability of my server.(after all, it is a small
server on my poor laptop....which use winXP and IIS......not
professional, huh?)

I configures IIS to terminate CGI program if it do not complete in 20
sec. But it does not work....Perhaps I should go to a IIS or apache
forum for answer.

Thank you.