This is an okay way to share config data, but this is not config data. You shouldn't share objects in this way.

To start with, you can't share DBI handles across a fork, i.e. you can't open a $dbh in startup.pl, httpd.conf, or any module used by a module called from one of those. Just use Apache::DBI.

Next, CGI is a really bizarre module that does lots of awful things with global variables. As a result, it is full of hacks to make it work under mod_perl. If you can, I suggest getting rid of it and using Apache::Request or CGI_Lite. It looks to me like you are not creating a new CGI object on every request here, which will definitely screw things up.

Finally, I wouldn't call these variables "shared". They are globals, and you are just using Exporter to shorten the namespace used for accessing them. You could skip all the Exporter stuff and just say $ISLog::Config::tt instead. And bear in mind that each apache child has a unique set of these variables, so any updates you make to them are not reflected in other apache children.