[hibernate-dev] HHH-9857 - Reuse of EntityEntry for bytecode enhanced read-only reference cached entities

[Sanne Grinovero]

There are lots of setters on EntityEntry, but sharing it would require
at least the implementation to be fully immutable to be threadsafe.

I see three options for the custom EntityEntry implementation:
 - simply ignore any write method by implementing each method as a no-op
 - throw exceptions on any write method
 - split the EntityEntry interface into a parent interface
"ReadOnlyEntityEntry" which doesn't have any such method

The first option seems the easy way out but we would not notice any
unintended / illegal usage; I'd prefer the third one but I'm not sure
which impact it would have, seems like a large change that needs
experimenting.

I just noticed an ImmutableEntityEntry implementation exists now, but
it's not actually immutable? That should be fixed, at very least the
javadoc to explain what that class purpose is?

Thanks,
Sanne

On 9 June 2015 at 13:03, John O'Hara <johara at redhat.com> wrote:
> For our use case, bytecode enhanced reference cached immutable entities,
> our top object for memory allocation is EntityEntry.
>
> We see an EntityEntry object created every time an immutable entity is
> added to a persistence context.
>
> In our use case, where we know the entity is immutable and we already
> have an EntityEntry cached, can we re-use the EntityEntry between
> sessions? This would reduce the allocation rate of EntityEntry in our
> use case by ~50%.
>
>
> --
> John O'Hara
> johara at redhat.com
>
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