Use of System.identityHashCode in org.drools.core.common.DefaultFactHandle -------------------------------------------------------------------------- Key: DROOLS-2361 URL: https://issues.jboss.org/browse/DROOLS-2361 Project: Drools Issue Type: Enhancement Components: core engine Affects Versions: 7.6.0.Final Reporter: Sidi Mohamed EL AATIFI Assignee: Mario Fusco Labels: performance Attachments: before.png This is a JVM https://bugs.openjdk.java.net/browse/JDK-6378256 bug has been fixed in JDK 9 It's not a bug in Drools but will be affected severely if using Drools for serious workloads. in my case 40% of CPU usage was to _java.lang.System.identityHashCode_ used by org.drools.core.common.DefaultFactHandle#determineIdentityHashCode !before.png|thumbnail! UPDATE: One possible solution is to introduce new (optional) interface for identityHashCode that can be implemented by user facts and internal facts. and provide identityHashCode backed by native (fast) hashCode