How are you and Saptar getting on with this challenge?
I did a little experiment this morning. The dhis.war is about 35M of
mostly compressed application and framework classes which is one of
the reasons why it is a herculean effort for tomcat to try and load it
multiple times into memory.
If you pull out all the WEB-INF/lib/*.jar files from the war and place
those into tomcat's lib directory you are left with a dhis.war which
is only 1.8M. (I did it on jetty, but same should apply to tomcat).
Everything continues to run as before and I suspect you will find that
you can now load gazillions of dhis2 instances without exhausting the
PermSize. Let me know how this works.
Of course the downside of de-packaging is that you will hit serious
complications if you are running different dhis2 versions which might
make use of different versions of libraries. It will be a case of
upgrade one - upgrade all.