So the sessions are maintained when switching to https if there is no load balacing. Are the sessions maintained with mod_jk + glassfish + load balancing for you if there is no switching http <-> https? Trying to determine if the issue is with mod_jk ssl or session/load balancing you have.
I assume you've set up your config as explained in
http://blogs.sun.com/jluehe/entry/supporting_apache_loadbalancer_with_glassfish
"List each GlassFish instance, including the port number of its mod_jk connector, in Apache's workers.properties configuration file. Make sure that the name of each worker equals the value of the jvmRoute system property of the GlassFish instance to which the worker connects. This convention makes it possible for an HTTP session to remain sticky to the GlassFish instance on which the session was created, or on which the session was last resumed. "
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