[jboss-jira] [JBoss JIRA] (DROOLS-2174) Deadlock between AbstractWorkingMemory and DefaultAgenda

[Umang Sharma (JIRA)]

    [ https://issues.jboss.org/browse/DROOLS-2174?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13504497#comment-13504497 ] 

Umang Sharma commented on DROOLS-2174:
--------------------------------------

This is right from one of our production servers. I don't have a shareable reproducer for this as of now. Would require some work for get to that. Would try and provide it in few days time.

For now, I would request you to investigate it from the perspective of the cloned bug. Because the stack traces are exactly same. Also if some workarounds can be suggested that would be great. 

Another point is that we already have an application level lock in place to ensure that no sessions are created while some rules are getting added/modified. Si is there a way we can bypass the Drools internal locking mechanism?

Also I would also like to know any best practices while using stateful sessions.

> 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 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.



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