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 Priority: Major Fix For: 6.0.0.CR2 I am getting a similar deadlock as the one in the cloned issue. We are using following dependencies: <dependency> <groupId>org.drools</groupId> <artifactId>drools-templates</artifactId> <version>$ {runtime.version}</version> </dependency> <dependency> <groupId>org.kie</groupId> <artifactId>kie-api</artifactId> <version>${runtime.version} </version> </dependency> <dependency> <groupId>org.drools</groupId> <artifactId>drools-core</artifactId> <version>$ {runtime.version}</version> </dependency> <dependency> <groupId>org.drools</groupId> <artifactId>drools-compiler</artifactId> <version>${runtime.version} </version> </dependency> runtime.version = 6.5.0-Final I have around 50 off threads stuck in a deadlock. 49 of them are having following stack trace: "THREAD-4" #124 prio=5 os_prio=0 tid=0x00000000015fc800 nid=0x3a5d waiting on condition [0x00007fc773e7b000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) parking to wait for <0x000000074d189818> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireShared(AbstractQueuedSynchronizer.java:967) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireShared(AbstractQueuedSynchronizer.java:1283) at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.lock(ReentrantReadWriteLock.java:727) at org.drools.core.impl.KnowledgeBaseImpl.readLock(KnowledgeBaseImpl.java:703) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulSession(KnowledgeBaseImpl.java:1434) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulSession(KnowledgeBaseImpl.java:1422) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulKnowledgeSession(KnowledgeBaseImpl.java:308) at org.drools.core.impl.KnowledgeBaseImpl.newKieSession(KnowledgeBaseImpl.java:385) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:693) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:629) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:611) And one of them is stuck in the following stack trace: "THREAD-4" #124 prio=5 os_prio=0 tid=0x00000000015fc800 nid=0x3a5d waiting on condition [0x00007fc773e7b000] java.lang.Thread.State: WAITING (parking) at sun.misc.Unsafe.park(Native Method) parking to wait for <0x000000074d189818> (a java.util.concurrent.locks.ReentrantReadWriteLock$NonfairSync) at java.util.concurrent.locks.LockSupport.park(LockSupport.java:175) at java.util.concurrent.locks.AbstractQueuedSynchronizer.parkAndCheckInterrupt(AbstractQueuedSynchronizer.java:836) at java.util.concurrent.locks.AbstractQueuedSynchronizer.doAcquireShared(AbstractQueuedSynchronizer.java:967) at java.util.concurrent.locks.AbstractQueuedSynchronizer.acquireShared(AbstractQueuedSynchronizer.java:1283) at java.util.concurrent.locks.ReentrantReadWriteLock$ReadLock.lock(ReentrantReadWriteLock.java:727) at org.drools.core.impl.KnowledgeBaseImpl.readLock(KnowledgeBaseImpl.java:703) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulSession(KnowledgeBaseImpl.java:1434) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulSession(KnowledgeBaseImpl.java:1422) at org.drools.core.impl.KnowledgeBaseImpl.newStatefulKnowledgeSession(KnowledgeBaseImpl.java:308) at org.drools.core.impl.KnowledgeBaseImpl.newKieSession(KnowledgeBaseImpl.java:385) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:693) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:629) at org.drools.compiler.kie.builder.impl.KieContainerImpl.newKieSession(KieContainerImpl.java:611) Please help us out in fixing this. Its a production system serving millions of users. PS: This is was reproduced under a medium load where we create 50 stateful sessions in parallel and also some rule were also getting added in the KieContainer at the same time.