[jboss-jira] [JBoss JIRA] (DROOLS-776) Deadlock trying to syncronize 'eager' field in DefaultAgenda (drools-worker thread and the other thread)

[Juan Carlos Garcia (JIRA)]

Juan Carlos Garcia created DROOLS-776:
-----------------------------------------

             Summary: Deadlock trying to syncronize 'eager' field in DefaultAgenda (drools-worker thread and the other thread)
                 Key: DROOLS-776
                 URL: https://issues.jboss.org/browse/DROOLS-776
             Project: Drools
          Issue Type: Feature Request
    Affects Versions: 6.2.0.Final
            Reporter: Juan Carlos Garcia
            Assignee: Mark Proctor


Migrating from drools 6.0.1.Final to 6.2.0.Final there seems to be a rare deadlock trying to syncronized the DefaultAgenda *eager* field, i have seen it only 2 or three times now as it seems very dificult to reproduce.

In our scenario the test is calling *kSession.fireUntilHalt()*  in a new  thread,   then in the main thread waiting for some events to happens (by calling in a loop: kSession.getObjects(new ClassObjectFilter(_clazz)))) and then  doing some other assert checks.

See the stacktrace below i took with jstack:

{code}
Java stack information for the threads listed above:
===================================================
"Thread-5":
	at org.drools.core.phreak.RuleExecutor.evaluateNetwork(RuleExecutor.java:92)
	- waiting to lock <0x00000000ff245780> (a org.drools.core.phreak.RuleExecutor)
	at org.drools.core.common.DefaultAgenda.evaluateEagerList(DefaultAgenda.java:1044)
	- locked <0x00000000ff3dab38> (a org.drools.core.util.LinkedList)
	at org.drools.core.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:996)
	at org.drools.core.common.DefaultAgenda.fireUntilHalt(DefaultAgenda.java:1258)
	at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:1333)
	at org.drools.core.impl.StatefulKnowledgeSessionImpl.fireUntilHalt(StatefulKnowledgeSessionImpl.java:1310)
	at bar.foo.AIDelayTest$1.run(AIDelayTest.java:101)
	at java.lang.Thread.run(Thread.java:745)
"drools-worker-2":
	at org.drools.core.common.DefaultAgenda.addEagerRuleAgendaItem(DefaultAgenda.java:287)
	- waiting to lock <0x00000000ff3dab38> (a org.drools.core.util.LinkedList)
	at org.drools.core.reteoo.PathMemory.queueRuleAgendaItem(PathMemory.java:159)
	at org.drools.core.reteoo.PathMemory.doUnlinkRule(PathMemory.java:133)
	- locked <0x00000000ff2457a0> (a org.drools.core.reteoo.PathMemory)
	at org.drools.core.reteoo.PathMemory.unlinkedSegment(PathMemory.java:173)
	at org.drools.core.reteoo.SegmentMemory.unlinkNode(SegmentMemory.java:203)
	at org.drools.core.reteoo.BetaMemory.unlinkNode(BetaMemory.java:100)
	at org.drools.core.reteoo.BetaNode.doDeleteRightTuple(BetaNode.java:377)
	at org.drools.core.reteoo.JoinNode.retractRightTuple(JoinNode.java:107)
	at org.drools.core.reteoo.ObjectTypeNode.doRetractObject(ObjectTypeNode.java:345)
	at org.drools.core.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java:337)
	at org.drools.core.reteoo.EntryPointNode.retractObject(EntryPointNode.java:381)
	at org.drools.core.common.NamedEntryPoint.delete(NamedEntryPoint.java:615)
	at org.drools.core.base.DefaultKnowledgeHelper.delete(DefaultKnowledgeHelper.java:495)
	at org.drools.core.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:486)
	at bar.foo.Rule_basic$u46$delayExecution$u46$01246876731.defaultConsequence(Rule_basic$u46$delayExecution$u46$01246876731.java:7)
	at bar.foo.Rule_basic$u46$delayExecution$u46$01246876731DefaultConsequenceInvokerGenerated.evaluate(Unknown Source)
	at bar.foo.Rule_basic$u46$delayExecution$u46$01246876731DefaultConsequenceInvoker.evaluate(Unknown Source)
	at org.drools.core.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1114)
	- locked <0x00000000ff3da978> (a org.drools.core.common.DefaultAgenda)
	at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:160)
	at org.drools.core.phreak.RuleExecutor.fire(RuleExecutor.java:112)
	- locked <0x00000000ff245780> (a org.drools.core.phreak.RuleExecutor)
	at org.drools.core.phreak.PhreakTimerNode$Executor.qevauateAndFireRule(PhreakTimerNode.java:485)
	at org.drools.core.phreak.PhreakTimerNode$TimerNodeJob$1.run(PhreakTimerNode.java:420)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
	at java.lang.Thread.run(Thread.java:745)

Found 1 deadlock.

{code}



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