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

[Yves Galante (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-2272?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_29608 ] 

Yves Galante commented on HHH-2272:
-----------------------------------

Hi,

I have make a new patch and a new test case (file 3 & 4) on hibernate trunk, and I have running Junit of the testsuite projet.

This patch optimize cascading operation by caching relation parent-child on a map.
Differently by the previous patch after cascading the map is  cleaned.

eventSource.getPersistenceContext().addChildParent(child, parent);
action.cascade(eventSource, child, entityName, anything, isCascadeDeleteEnabled);
eventSource.getPersistenceContext().removeChildParent(child);

The test case save and flush 10 * 551 objects.

Before patch save object with cascading is more slow when session size grows.
After patch time of save stay same at each loop. 

Output of the test case before the patch :

Save took 449 ms
Save took 669 ms
Save took 1042 ms
Save took 1464 ms
Save took 2481 ms
Save took 2741 ms
Save took 3807 ms
Save took 4344 ms
Save took 4975 ms
Save took 5251 ms
Total took 30906 ms

Output after the patch

Save took 445 ms
Save took 144 ms
Save took 164 ms
Save took 108 ms
Save took 93 ms
Save took 93 ms
Save took 93 ms
Save took 94 ms
Save took 91 ms
Save took 89 ms
Total took 4905 ms

> 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
>          Issue Type: Task
>          Components: core
>    Affects Versions: 3.2.0.ga
>         Environment: Hibernate 3.2.0 on Oracle 9.2
>            Reporter: Markus Heiden
>         Attachments: hack.patch, hibernate.zip, Number of call.jpg, patchCascading.patch, SaveTest.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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