[jboss-jira] [JBoss JIRA] (DROOLS-807) Stuck thread due to deadlock in ProjectClassLoader

Munish Kumar (JIRA) issues at jboss.org
Thu Jun 4 00:24:02 EDT 2015 

     [ https://issues.jboss.org/browse/DROOLS-807?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Munish Kumar closed DROOLS-807.
-------------------------------
    Resolution: Cannot Reproduce Bug


Closing this issue since there is nothing wrong with Drools code. It was HP diagnostic agent which was trying to load its own classes with Drools internal class loader and due to race condition, it resulted into deadlock.

> Stuck thread due to deadlock in ProjectClassLoader
> --------------------------------------------------
>
>                 Key: DROOLS-807
>                 URL: https://issues.jboss.org/browse/DROOLS-807
>             Project: Drools
>          Issue Type: Bug
>          Components: core engine
>    Affects Versions: 6.1.0.Final
>            Reporter: Munish Kumar
>            Assignee: Mario Fusco
>
> We see below deadlock information in our Production tomcat
> Found one Java-level deadlock:
> =============================
> "tomcat-http--74":
>   waiting to lock monitor 0x00007fae28022218 (object 0x00000000902d8d20, a org.drools.core.common.ProjectClassLoader),
>   which is held by "tomcat-http--36"
> "tomcat-http--36":
>   waiting to lock monitor 0x00007fae28042838 (object 0x000000009044e5b8, a org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader),
>   which is held by "Metrics Collection"
> "Metrics Collection":
>   waiting to lock monitor 0x00007fae28022218 (object 0x00000000902d8d20, a org.drools.core.common.ProjectClassLoader),
>   which is held by "tomcat-http--36"
> Java stack information for the threads listed above:
> ===================================================
> "tomcat-http--74":
>         at org.drools.core.common.ProjectClassLoader.loadClass(ProjectClassLoader.java:111)
>         - waiting to lock <0x00000000902d8d20> (a org.drools.core.common.ProjectClassLoader)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
>         at org.drools.core.base.ClassFieldAccessorCache.getClass(ClassFieldAccessorCache.java:121)
>         at org.drools.core.base.ClassFieldAccessorCache.getClassObjectType(ClassFieldAccessorCache.java:45)
>         at org.drools.core.reteoo.ClassObjectTypeConf.<init>(ClassObjectTypeConf.java:85)
>         at org.drools.core.common.ObjectTypeConfigurationRegistry.getObjectTypeConf(ObjectTypeConfigurationRegistry.java:72)
>         at org.drools.core.impl.StatefulKnowledgeSessionImpl.initInitialFact(StatefulKnowledgeSessionImpl.java:689)
>         at org.drools.core.impl.StatefulKnowledgeSessionImpl.<init>(StatefulKnowledgeSessionImpl.java:388)
>         at org.drools.core.impl.StatefulKnowledgeSessionImpl.<init>(StatefulKnowledgeSessionImpl.java:278)
>         
> "tomcat-http--36":
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:404)
>         - waiting to lock <0x000000009044e5b8> (a org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader)
>         at org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader.loadType(ProjectClassLoader.java:293)
>         at org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader.access$200(ProjectClassLoader.java:258)
>         at org.drools.core.common.ProjectClassLoader.loadType(ProjectClassLoader.java:140)
>         at org.drools.core.common.ProjectClassLoader.loadClass(ProjectClassLoader.java:115)
>         - locked <0x00000000902d8d20> (a org.drools.core.common.ProjectClassLoader)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
>         at org.drools.core.rule.JavaDialectRuntimeData$PackageClassLoader.loadClass(JavaDialectRuntimeData.java:640)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
>         at java.lang.Class.forName0(Native Method)
>         at java.lang.Class.forName(Class.java:348)
>         at org.mvel2.ParserConfiguration.checkForDynamicImport(ParserConfiguration.java:163)
>         at org.mvel2.ParserConfiguration.hasImport(ParserConfiguration.java:191)
>         at org.mvel2.ParserContext.hasImport(ParserContext.java:363)
>         at org.mvel2.compiler.AbstractParser.createPropertyToken(AbstractParser.java:1342)
>         at org.mvel2.compiler.AbstractParser.nextToken(AbstractParser.java:846)
>         at org.mvel2.compiler.ExpressionCompiler._compile(ExpressionCompiler.java:129)
>         at org.mvel2.compiler.ExpressionCompiler.compile(ExpressionCompiler.java:63)
>         at org.mvel2.MVEL.compileExpression(MVEL.java:810)
>         at org.drools.core.base.mvel.MVELCompilationUnit.compile(MVELCompilationUnit.java:429)
>         at org.drools.core.base.mvel.MVELCompilationUnit.getCompiledExpression(MVELCompilationUnit.java:240)
>         at org.drools.core.rule.constraint.MvelConstraint.createMvelConditionEvaluator(MvelConstraint.java:222)
>         at org.drools.core.rule.constraint.MvelConstraint.evaluate(MvelConstraint.java:206)
>         at org.drools.core.rule.constraint.MvelConstraint.isAllowed(MvelConstraint.java:173)
>         at org.drools.core.reteoo.AlphaNode.assertObject(AlphaNode.java:134)
>         at org.drools.core.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:502)
>         at org.drools.core.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:377)
>         at org.drools.core.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:288)
>         at org.drools.core.reteoo.EntryPointNode.assertObject(EntryPointNode.java:251)
>         at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:367)
>         at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:286)
>         at org.drools.core.common.NamedEntryPoint.insert(NamedEntryPoint.java:139)
>         at org.drools.core.command.runtime.rule.InsertElementsCommand.execute(InsertElementsCommand.java:93)
>         at org.drools.core.command.runtime.rule.InsertElementsCommand.execute(InsertElementsCommand.java:40)
>         at org.drools.core.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:155)
>         at org.drools.core.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:76)
>         at org.drools.core.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:321)
>         at com.amdocs.dc.ruleengine.service.RuleEngineServiceImpl.evaluateRules(RuleEngineServiceImpl.java:452)
>         at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>         at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>         at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>         at java.lang.reflect.Method.invoke(Method.java:497)
>         at com.amdocs.dc.applicationcontext.BusinessResponseProcessorServiceInvoker.invoke(BusinessResponseProcessorServiceInvoker.java:53)
>         at com.amdocs.dc.applicationcontext.spring.BusinessResponseProcessorInvocationHandler.invoke(BusinessResponseProcessorInvocationHandler.java:85)
>         at com.amdocs.dc.applicationcontext.spring.$Proxy121.evaluateRules(Unknown Source)
>         
> "Metrics Collection" #21 daemon prio=5 os_prio=0 tid=0x00007fae7883a000 nid=0x7276 waiting for monitor entry [0x00007fae27ffd000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
>         at org.drools.core.common.ProjectClassLoader$InternalTypesClassLoader.loadClass(ProjectClassLoader.java:284)
>         - waiting to lock <0x00000000902d8d20> (a org.drools.core.common.ProjectClassLoader)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
>         at java.lang.Class.forName0(Native Method)
>         at java.lang.Class.forName(Class.java:348)
>         at com.mercury.diagnostics.capture.metrics.CollectorControl.instantiateCollector(CollectorControl.java:470)
>         at com.mercury.diagnostics.capture.metrics.CollectorControl.initialize(CollectorControl.java:369)
>         at com.mercury.diagnostics.capture.metrics.CollectorAgent.validateInitialization(CollectorAgent.java:1020)
>         at com.mercury.diagnostics.capture.metrics.CollectorAgent.run(CollectorAgent.java:803)
>         at java.lang.Thread.run(Thread.java:745)
> and because of above, other HTTP Connector thread are stuck at
> "tomcat-http--42" #217 daemon prio=5 os_prio=0 tid=0x00007fae54153000 nid=0x7619 waiting for monitor entry [0x00007fae12d72000]
>    java.lang.Thread.State: BLOCKED (on object monitor)
> 	at org.drools.core.common.ProjectClassLoader.loadClass(ProjectClassLoader.java:111)
> 	- waiting to lock <0x00000000902e3e88> (a org.drools.core.common.ProjectClassLoader)
> 	at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
> 	at org.drools.core.base.ClassFieldAccessorCache.getClass(ClassFieldAccessorCache.java:121)
> 	at org.drools.core.base.ClassFieldAccessorCache.getClassObjectType(ClassFieldAccessorCache.java:45)
> 	at org.drools.core.reteoo.ClassObjectTypeConf.<init>(ClassObjectTypeConf.java:85)
> 	at org.drools.core.common.ObjectTypeConfigurationRegistry.getObjectTypeConf(ObjectTypeConfigurationRegistry.java:72)
> 	at org.drools.core.impl.StatefulKnowledgeSessionImpl.initInitialFact(StatefulKnowledgeSessionImpl.java:689)
> 	at org.drools.core.impl.StatefulKnowledgeSessionImpl.<init>(StatefulKnowledgeSessionImpl.java:388)
> 	at org.drools.core.impl.StatefulKnowledgeSessionImpl.<init>(StatefulKnowledgeSessionImpl.java:278)
> 	at org.drools.core.common.PhreakWorkingMemoryFactory.createWorkingMemory(PhreakWorkingMemoryFactory.java:21)
> 	at org.drools.core.impl.StatelessKnowledgeSessionImpl.newWorkingMemory(StatelessKnowledgeSessionImpl.java:133)
> 	at org.drools.core.impl.StatelessKnowledgeSessionImpl.execute(StatelessKnowledgeSessionImpl.java:309)



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