Hi, Building a package from source takes a lot of memory. In a project, I have about 50k rules and with guvnor I use this configuration -Xms64m -Xmx5512m -XX:MaxPermSize=256m and it works fine. Anyway, you have to give drools enough memory to build the package. Si increase Xmx to as much as needed. The only way to avoid that all runtimes use so much memory is to use Guvnor where you build the package (which means use a lot of memory) and then download a binary package from Guvnor. In a previous project the Guvnor configuration had the one above and each drools runtime was working in less than 500MB Regards Nicolas 2013/2/5 wang [via Drools] <ml-node+s46999n4022050h83(a)n3.nabble.com&gt; ----- Nicolas Héron -- View this message in context: http://drools.46999.n3.nabble.com/Drools-5-4-x-can-t-load-huge-rules-tp40... Sent from the Drools: User forum mailing list archive at Nabble.com.