[hibernate-dev] SingleTableEntityPersister memory footprint in 5.3

[Andrej Golovnin]

Hi,

> So, I analyzed the dumps yesterday evening. The problem is real, meaning
> his SessionFactory is consuming more than 1GB of memory for 600+ tables,
> some with a lot of attributes. So for sure, the model is a big one, …

No, it is still a small one. I work on a project with 2145 tables. And the SessionFactory
consumes on production systems ca 300-400MB with Hibernate 5.2. I haven’t
tested the project with Hibernate 5.3. But I doubt it would consume more memory.
Except the Hibernate team broke something again.

> but it
> would be nice to be more gentle with this type of configuration. I don't
> think it's something new to 5.3 though as it's not the first time we have
> this type of reports.
> 
>> From my observations, the problem mostly comes from:
> LegacyBatchingEntityLoader
> \_ loaders - EntityLoader
>    \_ staticLoadQuery - EntityLoadQueryDetails
>        \_ rootReturn - EntityReturnImpl
> 
> The largest LegacyBatchingEntityLoader I have in the dump takes more than 2
> MB.
> 
> Keep in mind that with a batch size of 50, we have 13 EntityLoaders for
> batch sizes of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 20 and 50, each loader
> taking ~ 200 KB.
> 
> We discussed some ideas yesterday with Steve.

And I have discussed it with the Hibernate team 6 years ago:

http://lists.jboss.org/pipermail/hibernate-dev/2012-May/008341.html

And my suggestion to create things lazily were ignored/rejected.
And I have ignored the opinion of the Hibernate team and implemented
my suggestions in my version of Hibernate and saved a lot of memory
in my project.

Btw. please ask the user whether he has a lot of abstract entity classes.
When yes, then ask him if it would be possible to convert this entity classes
to mapped supper-classes. This may help to reduce memory consumption too.

Best regards,
Andrej Golovnin