[hibernate-dev] Serializable SessionFactory

[Sanne Grinovero]

On 12 January 2018 at 16:58, Vlad Mihalcea <mihalcea.vlad at gmail.com> wrote:
> Sure, we need to profile it first.

I had started to create a micro-benchmark for it; unfortunately I had
to get back on more urgent things, but if someone is willing to let it
grow further, it's on github:
 - https://github.com/Sanne/orm-boostrap-benchmarks

> From what our users have told us, getting the metadata from the database
> takes some time and my
> goal was to identify whether we can do something about that.
>
> I'll come back once I have more info.

+1 thanks!

>
> Vlad
>
> On Thu, Jan 11, 2018 at 3:05 PM, Sanne Grinovero <sanne at hibernate.org>
> wrote:
>>
>> On 11 January 2018 at 12:39, Steve Ebersole <steve at hibernate.org> wrote:
>> > I just don't see how serializing a full SessionFactory to disk is a good
>> > idea.
>> >
>> > What do you mean by "avoiding (caching) the DB metadata retrieving the
>> > part"?
>>
>> I'm wondering too. I would be very cautious with that: if the
>> datasource connection is (temporarily) broken, because for example
>> Hibernate was restarted, we don't really know which assumptions will
>> still be true. The metadata is possibly no longer valid.
>>
>> You can't know for sure if the "development cycle" of the users isn't
>> including some step which makes changes to the database, or maybe even
>> updates it. I actually expect this to be common and this would cause a
>> lot of trouble.
>>
>> If we're willing to invest to make the ORM bootstrap faster, that's
>> great but we should work on identifying what is being slow and what
>> can be done without making it dangerous.
>>
>> >
>> > On Thu, Jan 11, 2018 at 2:08 AM Vlad Mihalcea <mihalcea.vlad at gmail.com>
>> > wrote:
>> >
>> >> Yes, out of the JVM. This PR allows the SF to be serialized to a file,
>> >> so
>> >> the next time we bootstrap, we reload the whole SF from the file
>> >> instead.
>> >>
>> >> There are many unforeseen issues probably related to this PR and it
>> >> might
>> >> hurt maintenance in the long-run.
>> >>
>> >> For this reason, I'm going to leave the PR open as-is, and investigate
>> >> whether we can bootstrap faster by avoiding (cacahing) the DB metadata
>> >> retrieving the part.
>> >>
>> >> Vlad
>> >>
>> >> On Wed, Jan 10, 2018 at 7:45 PM, Steve Ebersole <steve at hibernate.org>
>> >> wrote:
>> >>
>> >>> The SessionFactory being Serialized outside the VM?  Because otherwise
>> >>> it
>> >>> is already "serializable" via VM serialization hooks
>> >>> and org.hibernate.internal.SessionFactoryRegistry.  And I'm not so
>> >>> convinced we should support serializing it for "out of" VM use aside
>> >>> from
>> >>> what we already do which assumes the new target VM has a similarly
>> >>> named
>> >>> SessionFactory in its org.hibernate.internal.SessionFactoryRegistry.
>> >>>
>> >>> On Wed, Jan 10, 2018 at 11:20 AM Vlad Mihalcea
>> >>> <mihalcea.vlad at gmail.com>
>> >>> wrote:
>> >>>
>> >>>> Hi,
>> >>>>
>> >>>> While reviewing old PRs we have in the ORM project, I stumbled on
>> >>>> this
>> >>>> one
>> >>>> about serializing the SessionFactory.
>> >>>>
>> >>>> I created a new PR, rebased on top of the current master branch and
>> >>>> all
>> >>>> tests are passing fine.
>> >>>>
>> >>>> If anyone wants to take a look, this is the PR:
>> >>>>
>> >>>> https://github.com/hibernate/hibernate-orm/pull/2107
>> >>>>
>> >>>> I'm thinking we should integrate it in 5.3.Alpha and stabilize it if
>> >>>> there
>> >>>> are some unforeseen changes.
>> >>>>
>> >>>> The only drawback is that, if we allow the SF to be Serializable,
>> >>>> upgrading
>> >>>> will be much more difficult in case we change object structure.
>> >>>> We could make it clear that this might not be supported or use the
>> >>>> serialVersionUID to point to Hibernate version: major.minor.patch.
>> >>>>
>> >>>> The main benefit is that, for a microservices architecture, Hibernate
>> >>>> could
>> >>>> start much faster this way.
>> >>>>
>> >>>> Vlad
>> >>>> _______________________________________________
>> >>>> hibernate-dev mailing list
>> >>>> hibernate-dev at lists.jboss.org
>> >>>> https://lists.jboss.org/mailman/listinfo/hibernate-dev
>> >>>>
>> >>>
>> >>
>> > _______________________________________________
>> > hibernate-dev mailing list
>> > hibernate-dev at lists.jboss.org
>> > https://lists.jboss.org/mailman/listinfo/hibernate-dev
>
>