[rules-users] multi-threaded deadlock?

[Charles Binford]

All,

Drools 4.0.7. 

I have a single rulebase and three threads running stateless sessions
(each thread has it's own session).  All appears to work fine until I
try to dynamically update the packages in the rulebase.  That scenario
intermittently hangs on an apparent deadlock.  The documentation says,
"Packages can be added and removed at any time...", but maybe this
wasn't assuming a multi-threaded context?

The stack trace of my three threads is below. 
- Thread 10 is in the middle if fireAllRules
- Thread 12 is trying to add facts to its session
- thread 11 is trying to add a new package to the ruleBase, but seems to
be in some flavor of fireAllRules on the ruleBase even though there is
no session argument in this code path.

Am I breaking some fundamental drools rule for multi-threading?  Do I
need to lock out other sessions from activity while updating packages?

Thanks
Charles Binford



"Thread-10"
java.lang.Object.wait(Object.java)
java.lang.Object.wait(Object.java:485)
org.drools.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:106)
org.drools.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:195)
org.drools.common.AbstractWorkingMemory.getFactHandleByIdentity(AbstractWorkingMemory.java:604)
org.drools.base.DefaultKnowledgeHelper.update(DefaultKnowledgeHelper.java:98)
com.sun.evtl.pe.customerPolicy.adm.rules.Rule_turn_on_batch_0.consequence(Rule_turn_on_batch_0.java:8)
com.sun.evtl.pe.customerPolicy.adm.rules.Rule_turn_on_batch_0ConsequenceInvoker.evaluate(Rule_turn_on_batch_0ConsequenceInvoker.java:22)
org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:554)
org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:518)
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:475)
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:439)
com.sun.evtl.pe.common.PolicyManager.fireRules(PolicyManager.java:353)
com.sun.evtl.pe.customerPolicy.adm.rules.ArchiveMgrThrd.fireRules(ArchiveMgrThrd.java:132)
com.sun.evtl.pe.customerPolicy.adm.rules.ArchiveMgrThrd.runEngine(ArchiveMgrThrd.java:51)
com.sun.evtl.pe.customerPolicy.adm.msg.PolicyListenerThrd.run(PolicyListenerThrd.java:57)
java.lang.Thread.run(Thread.java:619)



"Thread-11"
org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:439)
org.drools.base.FireAllRulesRuleBaseUpdateListener.beforeRuleBaseUnlocked(FireAllRulesRuleBaseUpdateListener.java:29)
org.drools.event.RuleBaseEventSupport.fireBeforeRuleBaseUnlocked(RuleBaseEventSupport.java:168)
org.drools.common.AbstractRuleBase.unlock(AbstractRuleBase.java:361)
org.drools.common.AbstractRuleBase.addPackage(AbstractRuleBase.java:456)
com.sun.evtl.pe.common.PolicyManager.addPackage(PolicyManager.java:237)
com.sun.evtl.pe.customerPolicy.adm.rules.ArchiveMgr.loadNewUserRules(ArchiveMgr.java:170)
com.sun.evtl.pe.customerPolicy.adm.msg.PolicyListenerThrd.run(PolicyListenerThrd.java:78)
java.lang.Thread.run(Thread.java:619)



"Thread-12"
java.lang.Object.wait(Object.java)
java.lang.Object.wait(Object.java:485)
org.drools.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:106)
org.drools.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:195)
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:743)
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:704)
com.sun.evtl.pe.common.PolicyManager.insertSensor(PolicyManager.java:316)
com.sun.evtl.pe.customerPolicy.adm.rules.ArchiveMgrThrd.assertFacts(ArchiveMgrThrd.java:79)
com.sun.evtl.pe.customerPolicy.adm.rules.ArchiveMgrThrd.runEngine(ArchiveMgrThrd.java:50)
com.sun.evtl.pe.customerPolicy.adm.msg.PolicyListenerThrd.run(PolicyListenerThrd.java:57)
java.lang.Thread.run(Thread.java:619)