How to make logout from database server (ORACLE for example) when user closes its session

Hi all Is it possible to track such situations when http user closes connection to HTTP server to close opened persistent connections to the database? This connections is still active all the time (if using php not as CGI but as module for Apache) and when user trying to login next time PHP uses previously opened (by OCIPLogin for example) persistent connection (the same connection resource) - but this connection may be broken from the server side if its idle time is too long. So I found only way to restart my Apache + modphp from time to time. :( Thanks, Vlad