[jbosscache-dev] Re: Minutes from JBossCache and Hibernate conf call.

[Manik Surtani]

On 27 Oct 2006, at 16:36, Owen Taylor wrote:

> On Fri, 2006-10-27 at 15:40 +0100, Manik Surtani wrote:
>> First off, thanks to all who attended, it was a very useful session.
>> Please let me know if I have missed anything or if there are any
>> inaccuracies.
>
>> 1) Detail of Hibernate usage of JBoss Cache
>>
>> 	- Notion mismatch between a Cache put() - which is a write - and a
>> Hibernate put() - which is a read from a DB. A Hibernate update() is
>> effectively a write.
>> 		- This notion mismatch causes unnecessary locking in JBoss Cache
>> when doing a Cache put().
>> 	- Hibernate maintains 3 types of caches: for caching entities,
>> caching queries and caching collections
>> 	- Most other cache providers used are flat and non-replicated,
>> assumes each region is isolated
>> 		- Replicated EHCache not tested with Hibernate.
>> 	- Assumes other cache providers don't handle concurrency, Hibernate
>> wraps these in a ConcurrencyStrategy and handles locking separately.
>> 		- Hence to need to differentiate between a Hibernate put() and
>> update() as these both translate to a cache.put().
>> 		- JBoss Cache could be used this way, with IsolationLevel.NONE
>> 		- This is a waste though, as it prevents using JBoss Cache to it's
>> full potential.
>> 		- A good temp. solution for now.
>
> One thing I mentioned on the call is that ReadWriteStrategy  
> requires not
> just a distributed store for objects, but also distributed locking.
> It needs functions to synchronously lock/unlock a node across the
> cluster - a concept which is pretty alien to the current JBoss Cache
> code. (?)
>
> 						- Owen
>
>

True, that is a good point.  And thinking of hacking that in, it  
would actually make more sense to implement a proper  
putForExternalRead() solution.


--
Manik Surtani

Lead, JBoss Cache
JBoss, a division of Red Hat

Email: manik at jboss.org
Telephone: +44 7786 702 706
MSN: manik at surtani.org
Yahoo/AIM/Skype: maniksurtani