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Exception when undeploying JBoss Drools app

Answer 1

+1 A:

The cause of the problem is that drools tries to continue to work (See org.drools.audit.WorkingMemoryFileLogger.writeToDisk()) while the application is trying to shut down.

The fix is to kill this thread (ThreadedWorkingMemoryFileLogger) before shutting down the app.

Aaron Digulla 2010-07-19 15:40:52

Thanks for your answer, the exceptions are not endless any more but they are still thrown. I would like to remove them, too, so here is what I do:In the @PreDestroy Method of the MDB I call this cleanUp method of the pojo that uses the rules engine:<code>public void cleanUp() { // the ThreadedFileLogger decisionLogger.close(); // StatefulKnowledgeSession ksession.dispose(); ksession = null; // the KnowledgeBase kbase = null; }</code>I still get some of the above mentioned Exceptions, but they stop eventually. What can I do to avoid them completely?

Arne 2010-07-20 09:20:55

Make sure that the loggers actually run before you close them. The exception shows that the XML parser is started (which tells me that the logger is trying to load its config).

Aaron Digulla 2010-07-20 13:00:11

What I do to test this is putting some test facts into the rule engine. I delete the log before that and see a new log that shows the facts I just put in, so I think the logger is working. After that I undeploy the app and get those exceptions.

Arne 2010-07-21 07:17:26

Sorry, my brain wasn't working yesterday. The stacktrace shows that no XML parser is loaded but that ThreadedWorkingMemoryFileLogger is trying to look up a service ("META-INF/services/javax.xml.datatype.DatatypeFactory") during shutdown. That tells me that the logger is still active. Did you stop the logger before shutdown? Did you wait for it to terminate with `Thread.join()`?

Aaron Digulla 2010-07-21 07:42:04

I call the close() method on the logger, I can not join on the thread because it is encapsulated inside the logger. I call the close() method in the finalize() method of the pojo that uses it and I think it is too late. @PreDestroy would be earlier but that is called from the container during lifecycle management and I cannot say whether it is this or if the app is undeploying. What is the "normal" way to end a Drools app with this logger? What am I doing differently?

Arne 2010-07-21 14:58:52

To clarify: A MDB references a pojo which references the Drools objects (knowledge base, logger, etc). The container creates more than one MDB, but all use the same pojo. I use Glassfish 2.1, JEE 5, JSE 6, Drools 5.0.

Arne 2010-07-21 15:04:21

1. Don't use finalize(), especially not in an EJB environment. 2. You must find a way to synchronize the creation and destruction of your pojo with the app. I can't tell you how to do this from the top of my hat; I suggest to ask a question here.

Aaron Digulla 2010-07-22 13:55:20

OK, thank you very much for your help.

Arne 2010-07-22 15:41:21

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Exception when undeploying JBoss Drools app

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