2 Replies Latest reply on Jan 10, 2012 9:13 AM by daniell

    Memory Leak when calling @Destroy (with SFSBs)

    daniell
    daniell Jan 3, 2012 6:41 AM

      Hi!


      I've discovered a memory leak in our application and I think it is a bug in Seam. Here we go:


      We're using Seam 2.2.2.Final deployed in an EAR on JBoss AS 5.1.0.GA.


      In an example-project, we have 2 Seam components, one POJO and one SFSB. The POJO-component uses the SFSB-component via Seam-DI (@In). The POJO-component has a method annotated with @Destroy.


      We are using the POJO-component in a (long-running-)conversation. Thus, the TestComponentA as well as the TestEJB will be created.
      When the conversation is ended and all components will be removed, the @Destroy-methods of all seam-components are called one after each other. The order, the @Destroy-methods are called, depend on the hashCode of the seam-name of the components (the component-names are put into an java.util.HashSet in the method org.jboss.seam.contexts.ServerConversationContext.getNamesFromSession() - the for-loop of the method org.jboss.seam.contexts.Contexts.destroy iterates over this HashSet afterwards).


      In the following example, the component-names have been chosen in this way, that the TestEJB will be removed before the TestComponentA is removed. So see the call-sequence:



      1. the SFSB-component is destroyed by seam - the container removes the SFSB

      2. the @Destroy-method of the POJO-component is called. But before, Seam-DI creates a new SFSB-component TestEJB because of the @In-annotation

      3. the POJO-component is removed by the GC

      4. the SFSB-component is still present



      It is easy to see that there are unused SFSBs via the jmx-console or in the server-log:


      10:56:31,693 ERROR [STDERR] TestEJB.postConstruct() called
10:56:31,693 ERROR [STDERR] tca created
[...]
10:59:36,518 ERROR [STDERR] TestEJB.discard() called
10:59:36,518 ERROR [STDERR] TestEJB.preDestroy() called
10:59:36,519 ERROR [STDERR] TestEJB.postConstruct() called
10:59:36,519 ERROR [STDERR] tca destroyed



      To reproduce the bug, 2 simple Components have been created. This is the SFSB-Component:


      @Stateful
@Name(TestEJB.SEAM_NAME)
@Interceptors(SeamInterceptor.class)
@JndiName(TestEJBLocal.JNDI_NAME)
@Scope(ScopeType.CONVERSATION)
@AutoCreate
public class TestEJB implements TestEJBLocal
{
    public static final String SEAM_NAME = "tcb";
    
    @Remove
    public void discard()
    {
        System.err.println("TestEJB.discard() called");
    }

    @PostConstruct
    public void postConstruct()
    {
        System.err.println("TestEJB.postConstruct() called");
    }

    @PreDestroy
    protected void preDestroy()
    {
        System.err.println("TestEJB.preDestroy() called");
    }
}


      ...and it's local-interface:


      @Local
public interface TestEJBLocal
{
    /** The local JNDI name for this EJB. */
    final static String JNDI_NAME = "ejb/project/TestEJB/local";
    
    public void discard();
}


      Last but not least the POJO-Component:


      @Scope(ScopeType.CONVERSATION)
@Name(TestComponentA.SEAM_NAME)
@AutoCreate
public class TestComponentA implements Serializable
{
    public static final String SEAM_NAME = "tcd";
    private static final long serialVersionUID = 7550180731244593255L;

    @In(value=TestEJB.SEAM_NAME)
    private TestEJBLocal testEJB;

    @Create
    public void create() {
        System.err.println("tca created");
    }

    @Destroy
    public void destroy() {
        System.err.println("tca destroyed");
    }
}



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