[hibernate-issues] [Hibernate-JIRA] Created: (HHH-2169) L2 Cache and Long transactions Memory Leak : OutOfMemoryException

[Sami Dalouche (JIRA)]

L2 Cache and Long transactions Memory Leak : OutOfMemoryException
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         Key: HHH-2169
         URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2169
     Project: Hibernate3
        Type: Bug

  Components: core  
    Versions: 3.2.0.ga    
 Environment: [b]Hibernate version:[/b] 
Hibernate Entity Manager 3.2.0, with Hibernate Core 3.2.0 and Hibernate Annotations 3.2.0

[b]Mapping documents:[/b]
Annotations

[b]Full stack trace of any exception that occurs:[/b]
Memory Heap Exception

[b]Name and version of the database you are using:[/b]
PosgreSQL 8.1


    Reporter: Sami Dalouche


Summary
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When enabling L2 Cache (with either OScache and EhCache, both with a limitation on the max #of instances, so the problem shouldn't come from the cache manager), Hibernate cannot have long running transactions, otherwise, it results in a Memory Heap Exception...

The problem does NOT happen if the L2 Cache is disabled !

Details
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- Configure the code to run in ONE transaction
- Have a huge loop that inserts 2 million entries that are cacheable (@Cache(usage = CacheConcurrencyStrategy.NONSTRICT_READ_WRITE)) 
- flush() and clear() every 1000 entries, to periodically flush the cache

=> None of the entries are garbage collected. 

=> Using a profiler, it is possible to trace the owning objects of my domain classes to :
- org.hibernate.action.EntityInsertAction ("instance" variable)
- array / List (variable elementData)
- variable "executions" in object .. class org.hibernate.engine.ActionQueue

Remarks :
- If the Query Cache is disabled, and the objects being inserted are NOT cacheable (no @Cache annotation), there is no problem
- If the Query Cache is enabled, then, no matter whether the objects being inserted are cacheable or not, The entries are never garbage collected, and I get an OutOfMemoryException. (I see NO relationship between the Query Cache and my objects. I never query the objects, only save them !!)


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