Umang Sharma created DROOLS-2174: ------------------------------------ Summary: Deadlock between AbstractWorkingMemory and DefaultAgenda Key: DROOLS-2174 URL: https://issues.jboss.org/browse/DROOLS-2174 Project: Drools Issue Type: Bug Affects Versions: 5.5.0.Final Reporter: Umang Sharma Assignee: Mario Fusco Fix For: 6.0.0.CR2 I experienced a deadlock when running in STREAM mode and using negative patterns with temporal constraints. When the rule gets fired by the installed timer job and at the same time another thread is firing rules, a deadlock can occur: 1. [rule firing thread] StatefulKnowledgeSessionImpl.execute(StatefulKnowledgeSessionImpl.java:820) acquires lock in AbstractWorkingMemory 2. [timer-thread] DefaultAgenda.fireActivation() call of synchronized method 3. [rule firing thread] DefaultAgenda.fireActivation() synchronized method, wait for other thread to exit synchornized method 4. [timer-thread] AbstractWorkingMemory.getGlobal() tries to access a global, tries to acquire lock in AbstractWorkingMemory which is held by the other thread --> Deadlock Excerpt from thread dump: "http-thread-pool-8082(374)": at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1264) - waiting to lock <0x00007f50407e4950> (a org.drools.common.DefaultAgenda) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221) at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1456) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:679) at org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:234) at org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:102) at org.drools.command.runtime.rule.FireAllRulesCommand.execute(FireAllRulesCommand.java:32) at org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:155) at org.drools.command.runtime.BatchExecutionCommandImpl.execute(BatchExecutionCommandImpl.java:76) at org.drools.impl.StatefulKnowledgeSessionImpl.execute(StatefulKnowledgeSessionImpl.java:821) "pool-4251-thread-1": at sun.misc.Unsafe.park(Native Method) - parking to wait for 0x00007f503fc71a20> (a java.util.concurrent.locks.ReentrantLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:158) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:747) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireQueued(AbstractQueuedSynchronizer.java:778) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.java:1114) at java.util.concurrent.locks.ReentrantLock$NonfairSync.lock(ReentrantLock.java:186) at java.util.concurrent.locks.ReentrantLock.lock(ReentrantLock.java:262) at org.drools.common.AbstractWorkingMemory.getGlobal(AbstractWorkingMemory.java:634) at myrules.Rule_ruleWithTimeout_ece4a3c9fc2741a4ab97a92b77611203DefaultConsequenceInvokerGenerated.evaluate(Unknown Source) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1287) - locked <0x00007f50407e4950> (a org.drools.common.DefaultAgenda) at org.drools.common.DefaultAgenda.fireTimedActivation(DefaultAgenda.java:1344) - locked <0x00007f50407e4950> (a org.drools.common.DefaultAgenda) at org.drools.common.Scheduler$ActivationTimerJob.execute(Scheduler.java:83) -- This message was sent by Atlassian JIRA (v7.5.0#75005)