[hibernate-dev] HHH-13916 / WFLY-13259

[Gail Badner]

Hi Sanne,

I've reworked HHH-13916 <https://hibernate.atlassian.net/browse/HHH-13916> to
use this alternative, and set the fix version to 6-wishlist.

Regards,
Gail

On Tue, Apr 14, 2020 at 1:23 AM Sanne Grinovero <sanne at hibernate.org> wrote:

> Hi Gail,
>
> I would go ahead with this improvement for ORM 6 and avoid spending
> your precious time on a v5 improvement - especially if it's going to
> require coordination with both the Infinispan and WildFly teams.
>
> Thanks
>
> On Fri, 10 Apr 2020 at 00:56, Gail Badner <gbadner at redhat.com> wrote:
> >
> > I've been looking into how to fix this issue:
> >
> > https://hibernate.atlassian.net/browse/HHH-13916
> > https://issues.redhat.com/browse/WFLY-13259
> >
> > The crux of the matter is when Hibernate calls
> CacheHelper.fromSharedCache(
> > session, cacheKey, cachAccess ), and the entity is not found in the
> cache,
> > Infinispan stores a PendingPut containing a
> > SharedSessionContractImplementor instance.
> >
> > IIUC, as an optimization, Infinispan assumes that the entity not found in
> > the cache will ultimately be added to the cache after it is loaded from
> the
> > database. If that doesn't happen, the PendingPut will expire and will
> > eventually be removed. Until it expires,
> > the SharedSessionContractImplementor instance cannot be
> garbage-collected.
> >
> > This is particularly a problem if the cache is not disabled while a large
> > amount of cacheable data is being imported. This is the particular use
> case
> > described by WFLY-13259. There is a reproducer attached that
> > throws OutOfMemoryError.
> >
> > The obvious workaround is to set org.hibernate.CacheMode.IGNORE (or
> > possibly CacheMode.PUT?) while importing data.
> >
> > I discussed this briefly with Sanne, and we agree that an improvement
> would
> > be to not store a SharedSessionContractImplementor in a PendingPut at
> all.
> >
> > There is already a way to get a UUID for the session by calling
> > SharedSessionContractImplementor#getSessionIdentifier(). Unfortunately,
> the
> > implementation in AbstractSharedSessionContract indicates that frequent
> > "UUID generations will cause a significant amount of contention".
> >
> > Sanne has suggested returning a "token" that is just a new Object. I've
> > created a branch
> > <https://github.com/gbadner/hibernate-core/tree/HHH-13916_token> [1]
> that
> > does this.
> >
> > Infinispan would need to be updated so that PendingPut#owner is set
> > to SharedSessionContractImplementor#getSessionToken() (instead of
> > the SharedSessionContractImplementor object).
> >
> > Looking at the Infinispan code, I see that code that would be affected is
> > in
> > org.infinispan.hibernate.cache.commons.access.PutFromLoadValidator, which
> > is used by infinispan-hibernate-cache-v51.
> >
> > IIUC, in order to fix this any time soon for WildFly or EAP 7.x, [1]
> would
> > have to be backported to both Hibernate ORM 5.1 and 5.3 branches, and the
> > Hibernate versions would have to be updated in Infinispan before
> Infinispan
> > could be updated to use
> SharedSessionContractImplementor#getSessionToken().
> >
> > Galder/Radim, are there any plans for
> > dropping infinispan-hibernate-cache-v51?
> >
> > Are there other places where the SharedSessionContractImplementor is
> stored
> > in the cache?
> >
> > Aside from infinispan-hibernate-cache-v51, do you see anything about [1]
> > that would cause problems?
> >
> > If not, when do you think we could coordinate this change? Do we need to
> > wait for Hibernate ORM 6.0?
> >
> > This is considered an improvement, so it's not urgent. It would be nice
> to
> > fix this though.
> >
> > Galder/Radim, please provide your input so we figure out when it can be
> > fixed.
> >
> > Thanks,
> > Gail
> >
> > [1] https://github.com/gbadner/hibernate-core/tree/HHH-13916_token
> > [2]
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> >
>
>