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

[Sami Dalouche (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2169?page=comments#action_24936 ] 

Sami Dalouche commented on HHH-2169:
------------------------------------

One last remark I forgot :
- If L2 Cache is disabled and Query Cache is disabled, there is no problem.

> L2 Cache and Long transactions Memory Leak : OutOfMemoryException
> -----------------------------------------------------------------
>
>          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
> ---------
> 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
> ----------
> - 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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