I would say no. I think that every session has its own RETE nodes filled with its own facts. May be the different RETE instances share some evaluators (or at least generated dynamic classes that represent nodes) so it could use a bit less memory than recreating the same kbase again and again (which can affect PermGenSpace on some jvm where GC is not good at purging the permgen). But the real perf hit should be due to using multiple Thread in a single jvm : if you add too much threads, gc, swap and so on can become long. To test that may be you can test with using the same kbase for all session, and test the same with creating a new kbase for each session, and then compare the perfs (ignoring objects creation of course) ... ... and post the results back here :) My own experience of usage of multi-thread with rules is for chaining multiple "rule box" having distinct kbase, so I never tried that. ----- Mail original ----- De: "gboro54" <gboro54@> À: rules-users@.jboss Envoyé: Jeudi 10 Mai 2012 19:12:28 Objet: [rules-users] Knowledge Base and Multiple Sessions If you have multiple sessions running on different threads against the same knowledge base, is there any performance hit during evaluation? -- View this message in context: http://drools.46999.n3.nabble.com/Knowledge-Base-and-Multiple-Sessions-tp... Sent from the Drools: User forum mailing list archive at Nabble.com. _______________________________________________ rules-users mailing list rules-users@.jboss https://lists.jboss.org/mailman/listinfo/rules-users _______________________________________________ rules-users mailing list rules-users@.jboss https://lists.jboss.org/mailman/listinfo/rules-users