[hibernate-issues] [Hibernate-JIRA] Updated: (HHH-2272) Serious performance problems when saving large amount of transient entities with collections of transient entities

[Markus Heiden (JIRA)]

     [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2272?page=all ]

Markus Heiden updated HHH-2272:
-------------------------------

    Attachment: hack.patch

Here is my hack for fixing this issue. It is a patch against the src folder of hibernate 3.2.0 ga. This patch is currently just implemented for the save-update cascade, but may be (should be?) applied to other cascading actions too. It includes the hack which fixes HHH-1612.

I wasn't able to get all tests running without failure on the unpatched hibernate source, so I cannot promise that this patch won't break any tests. I am not enough in hibernate to promise that the new cache in StatefulPersistenceContext won't produce any memory leaks.

I hope you check this patch soon, rework it and release it with the next minor release :-)

> Serious performance problems when saving large amount of transient entities with collections of transient entities
> ------------------------------------------------------------------------------------------------------------------
>
>          Key: HHH-2272
>          URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2272
>      Project: Hibernate3
>         Type: Task

>   Components: core
>     Versions: 3.2.0.ga
>  Environment: Hibernate 3.2.0 on Oracle 9.2
>     Reporter: Markus Heiden
>  Attachments: hack.patch, hibernate.zip
>
>
> When saving many (e.g. 50000) transient entities with a collection of transient entities, for each collection element the whole persistence context is searched (by StatefulPersistenceContext#getIndexInOwner() and StatefulPersistenceContext#getOwnerId) and its even searched twice when the collection is an indexed collection. This leads to an enormous amount (> 1000000) of iterations over all entities and over all collection elements of each entity. Especially when one saves only the same type of entities this leads to times of hours(!) even on a fast machine before any insert statement is even issued. This issue is related to HHH-1612, but fixing issue HHH-1612 won't resolve this problem (I have explored this with a hack which fixes HHH-1612).
> In my eyes there are two ways to solve this problem:
> 1) When cascading the save of a parent, the parent cascade can fill the persistence context with information about its collection elements. E.g. before cascading the save to a collection a parent can add  a (child, parent) pair to a map in the persistence context to avoid the above described iterations. Then a simple Map#get() would be sufficient in most cases to get the parent.
> 2) When cascading, the parent has to be passed with the cascaded (e.g. saved) element. But this is no good solution, because it affects some well known hibernate apis.

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