ThreadSafeTrackableTimeJobFactoryManager for default ---------------------------------------------------- Key: DROOLS-3089 URL: https://issues.jboss.org/browse/DROOLS-3089 Project: Drools Issue Type: Enhancement Components: core engine Affects Versions: 7.12.0.Final Reporter: Toshiya Kobayashi Assignee: Maciej Swiderski Priority: Major Labels: support By default, TrackableTimeJobFactoryManager is set by SessionConfigurationImpl. https://github.com/kiegroup/drools/blob/7.11.0.Final/drools-core/src/main... If users access a ksession via multiple threads, it would potentially hit a HashMap concurrency issue (e.g. https://stackoverflow.com/questions/22944918/why-does-the-code-hang-with-...). ThreadSafeTrackableTimeJobFactoryManager is bundled for multi-thread use. You can use it by Drools 7: {noformat} System.setProperty("drools.timerJobFactory", "thread_safe_trackable"); {noformat} Drools 6.3+: {noformat} KieSessionConfiguration kconf = KnowledgeBaseFactory.newKnowledgeSessionConfiguration(); ((org.drools.core.SessionConfiguration)kconf).setTimerJobFactoryType( TimerJobFactoryType.THREAD_SAFE_TRACKABLE ); KieSession ksession = kContainer.newKieSession("ksession-name", kconf); {noformat} However, it's better to make ThreadSafeTrackableTimeJobFactoryManager default because "Suddenly hitting an issue in production" is significant than "small overhead by ConcurrentHashMap". (Generally, users are not very conscious about "it is accessed by multi-threads or not")