parallelRulesBuildThreshold must also be set in KnowledgeBuilderImpl(InternalKnowledgeBase kBase, KnowledgeBuilderConfigurationImpl configuration) constructor. --------------------------------------------------------------------------------------------------------------------------------------------------------------- Key: DROOLS-2494 URL: https://issues.jboss.org/browse/DROOLS-2494 Project: Drools Issue Type: Enhancement Components: core engine Affects Versions: 7.7.0.Final Reporter: Duncan Doyle Assignee: Duncan Doyle The new parallelRulesBuildThreshold configuration option is not set in the KnowledgeBuilderImpl(InternalKnowledgeBase kBase, KnowledgeBuilderConfigurationImpl configuration) constructor, causing it to default to "0", which basically always enables the parallel build.