Concurrency issue: Invalid bytecode generated by KnowledgeBuilder.add() ----------------------------------------------------------------------- Key: JBRULES-3283 URL: https://issues.jboss.org/browse/JBRULES-3283 Project: JBRULES Issue Type: Bug Security Level: Public(Everyone can see) Components: drools-compiler (expert) Affects Versions: 5.3.0.CR1, 5.3.0.Final Environment: Oracle Java 6, Oracle Java 7, Linux, MacOS java version "1.6.0_26" Java(TM) SE Runtime Environment (build 1.6.0_26-b03-384-10M3425) Java HotSpot(TM) 64-Bit Server VM (build 20.1-b02-384, mixed mode) Reporter: Thomas Kruse Assignee: Mario Fusco Priority: Minor Fix For: 5.4.0.Beta2 Attachments: drools53.tgz Since Drools 5.3.0.CR1 concurrent creation of different knowledgebases from filesystem DRL rule definition leads to illegal bytecode. Reproduceable with Janino and eclipse compiler. I have a maven based test project which executes the unit tests in parallel, this is the result: {code} runFirst(de.trion.drools53.TwoTest): -1 runFirst(de.trion.drools53.FourTest): (class: de/trion/drools53/Rule_When_a_user_is_young__print_his_name_DefaultConsequenceInvoker, method: equals signature: (Ljava/lang/Object;)Z) Expecting to find integer on stack runSecond(de.trion.drools53.FourTest): (class: de/trion/drools53/Rule_When_a_user_is_young__print_his_name_DefaultConsequenceInvoker, method: equals signature: (Ljava/lang/Object;)Z) Expecting to find integer on stack runFirst(de.trion.drools53.OneTest): (class: de/trion/drools53/Rule_When_a_user_is_young__print_his_name_DefaultConsequenceInvoker, method: equals signature: (Ljava/lang/Object;)Z) Expecting to find integer on stack runFirst(de.trion.drools53.ThreeTest): (class: de/trion/drools53/Rule_When_a_user_is_young__print_his_name_DefaultConsequenceInvoker, method: equals signature: (Ljava/lang/Object;)Z) Incompatible object argument for function call runSecond(de.trion.drools53.ThreeTest): (class: de/trion/drools53/Rule_When_there_is_god__the_light_always_shines_DefaultConsequenceInvoker, method: equals signature: (Ljava/lang/Object;)Z) Unable to pop operand off an empty stack {code} Workaround: synchronize access Not affected: Drools 5.3.0.Beta