[jboss-jira] [JBoss JIRA] (DROOLS-368) Memory leak mappedKnowledgeBaseListeners

[David Tse (JIRA)]

David Tse created DROOLS-368:
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             Summary: Memory leak mappedKnowledgeBaseListeners
                 Key: DROOLS-368
                 URL: https://issues.jboss.org/browse/DROOLS-368
             Project: Drools
          Issue Type: Bug
      Security Level: Public (Everyone can see)
    Affects Versions: 5.5.0.Final
         Environment: Linex
            Reporter: David Tse
            Assignee: Mark Proctor
            Priority: Critical


This leak is identified by getting a heap dump.  Analysis of the heap dump by Eclipse MAT puts org.drools.retoo.ReteooRuleBase as the prime suspect holding to 47.33% of the 870 MB heap memory with org.drools.retoo.ReteooStatefulSession adding to the problem accounting for an additional 5.25% of the memory leak. 


Examination of the BRMS 5.5.0.Final source code indicates that SFT memory leaks are caused by issues associated with 7 classes in the drools-core module of the community version BRMS 5.5.0.Final.  These classes are
•	org.drools.impl.KnowledgeBaseImpl.java
•	org.drools.impl.StatefulKnowledgeSession.java
•	org.drools.retoo.ReteooStatefulSession which extends org.drools.retoo.ReteooWorkingMemory.java which extends org.drools.common.AbstractWorkingMemory.java
•	org.drools.retoo.ReteooRuleBase.java which extends org.drools.common.AbstractRuleBase.java

The code in the community version has cyclic dependency and these developed into dying pointers. 
1.	org.drools.impl.KnowledgeBaseImpl$KnowledgeBaseEventListenerWrapper is holding a reference to this (KnowledgeBaseImpl)
2.	KnowledgeBaseImpl is holding a reference to RuleBase (ReteooRuleBase is the implementation class)
3.	ReteooRuleBase is holding a reference to org.drools.impl.KnowledgeBaseImpl$KnowledgeBaseEventListenerWrapper

For the second leak, StatefulKnowledgeSessionImpl is holding a reference to ReteooWorkingMemory.  ReteooWorkingMemory is also holding a reference to StatefulKnowledgeSessionImpl.  


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