[jboss-jira] [JBoss JIRA] (WFLY-9849) Hibernate session related leak on module undeployment

[Scott Marlow (JIRA)]

    [ https://issues.jboss.org/browse/WFLY-9849?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13585704#comment-13585704 ] 

Scott Marlow commented on WFLY-9849:
------------------------------------

For example, one of the weak references to the org.hibernate.internalSessionFactoryImpl is:
{code}
Class Name                                                                                                        | Ref. Objects | Shallow Heap | Ref. Shallow Heap | Retained Heap
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
class java.lang.reflect.Proxy @ 0xe01da968 System Class                                                           |            1 |           24 |               144 |         7,152
'- proxyClassCache java.lang.reflect.WeakCache @ 0xe00ea488                                                       |            1 |           32 |               144 |         7,088
   '- map java.util.concurrent.ConcurrentHashMap @ 0xe00ea4d8                                                     |            1 |           64 |               144 |         4,208
      '- table java.util.concurrent.ConcurrentHashMap$Node[16] @ 0xe00ea518                                       |            1 |           80 |               144 |         4,144
         '- [2] java.util.concurrent.ConcurrentHashMap$Node @ 0xff265af0                                          |            1 |           32 |               144 |         1,376
            '- next java.util.concurrent.ConcurrentHashMap$Node @ 0xff265f60                                      |            1 |           32 |               144 |           464
               '- key java.lang.reflect.WeakCache$CacheKey @ 0xff265f80                                           |            1 |           32 |               144 |            32
                  '- referent org.jboss.modules.ModuleClassLoader @ 0xe077cde8                                    |            1 |           88 |               144 |       161,776
                     '- classes java.util.Vector @ 0xe077cf48                                                     |            1 |           32 |               144 |        65,312
                        '- elementData java.lang.Object[2560] @ 0xff1d0588                                        |            1 |       10,256 |               144 |        65,280
                           '- [1448] class org.hibernate.proxy.pojo.javassist.JavassistProxyFactory$2 @ 0xff2049c0|            1 |            0 |               144 |             0
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
{code}
I'll look again at the heap dump that you posted and verify if the leaked session factories have strong references.

> Hibernate session related leak on module undeployment
> -----------------------------------------------------
>
>                 Key: WFLY-9849
>                 URL: https://issues.jboss.org/browse/WFLY-9849
>             Project: WildFly
>          Issue Type: Bug
>    Affects Versions: 11.0.0.Final, 12.0.0.Final
>         Environment: * Ubuntu 16.04.3 LTS
> * OpenJDK 1.8.0_151
> * Wildfly 11.0.0.Final
> Seems to occur at least on CentOS 7/OpenJDK 1.8.0_151 also.
>            Reporter: Joni Syri
>            Assignee: Scott Marlow
>
> In some cases it seems that removing deployment from the Wildfly, doesn't free up {{org.hibernate.internal.SessionFactoryImpl}}- instance related to the deployment. (plus some other Hibernate related classes). This can be seen by taking memory dump with VisualVM and looking up {{SessionFactoryImpl}} instances. 
> This leads to cumulative memory leak in cases, where application is repeatedly deployed/undeployed (or updated).
> updated: Seems to occur on 12.0.0.Final also
> Memory dumps can be found at https://drive.google.com/drive/folders/1WbHB6hRpr_lrc4yb4yxWLpeObmJlNCzD (wildfly-leak-1 is after first deployment, wildfly-leak-2 after few re-deploys)
> server.log https://drive.google.com/file/d/1I32OTnPWeopVEtRC3ol-pjkH2dlkLizD/view?usp=sharing



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