Question

我们已经使用Drools设置了基本的Guvnor UI框架。规则是由半技术人员编写的，并且存在错误范围（范围始终存在，无论是谁写的:)）

昨天，有人编写了一条规则，开始抛出NullPoiterException，但Drool似乎将此异常包装成CYCLIC_DEPENDENCY_ERROR并显示相同的内容。

此外，在此问题发生后，我们立即（3-4分钟）结束了OOM java.lang.OutOfMemoryError: Java heap space。

Stacktrace了解详情：

Feb 2013 08:06:55,447 [ERROR]  (SWF Activity  DroolsActivityTaskList-2.2 229) com.amazon.mobius.csi.workers.droolsengine.DroolsEngineActivitiesImpl:runRules:220 [CYCLIC_DEPENDENCY_ERROR]: Error
 while executing Rules, Please validate all rules against any cyclic dependency
Exception executing consequence for rule "final NON EC" in com.amazon.mobius.csi.workers.droolsengine: java.lang.NullPointerException
        at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39)
        at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1101)
        at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1029)
        at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1251)
        at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:708)
        at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:672)
        at org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:218)
        at org.drools.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:295)
        at com.amazon.mobius.csi.workers.droolsengine.DroolsEngineActivitiesImpl.runRules(DroolsEngineActivitiesImpl.java:216)
        at com.amazon.mobius.csi.workers.droolsengine.DroolsEngineActivitiesImpl.executeRules(DroolsEngineActivitiesImpl.java:145)
        at sun.reflect.GeneratedMethodAccessor173.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at com.amazonaws.services.simpleworkflow.flow.pojo.POJOActivityImplementation.execute(POJOActivityImplementation.java:63)
        at com.amazonaws.services.simpleworkflow.flow.generic.ActivityImplementationBase.execute(ActivityImplementationBase.java:46)
        at com.amazonaws.services.simpleworkflow.flow.worker.SynchronousActivityTaskPoller.execute(SynchronousActivityTaskPoller.java:214)
        at com.amazonaws.services.simpleworkflow.flow.worker.ActivityTaskPoller$2.run(ActivityTaskPoller.java:95)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.NullPointerException
        at com.amazon.mobius.csi.workers.droolsengine.Rule_final_NON_EC.defaultConsequence(Unknown Source)
        at com.amazon.mobius.csi.workers.droolsengine.Rule_final_NON_ECDefaultConsequenceInvoker.evaluate(Unknown Source)
        at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1091)
        ... 18 more

为什么Drools将其视为CYCLIC_DEPENDENCY并导致OOM？我们还有其他问题吗？任何帮助将不胜感激。

谢谢，

Answer 1

我认为这是规则之间的循环依赖。一条规则的RHS正在激活另一条规则，而另一条规则的RHS又会激活第一条规则。因此，存在无限循环的规则激活。

如果没有看到规则本身，我建议设置一个议程事件监听器来记录触发的规则。这样你就应该能够看到以这种方式激活哪两条规则。这样的日志记录侦听器的示例如下：

https://github.com/gratiartis/scattercode-drools-scenarios/blob/master/src/main/java/uk/co/scattercode/drools/util/TrackingAgendaEventListener.java

drools规则中的NPE导致CYCLIC_DEPENDENCY和OOM

1 个答案: