So I started breaking out 3.3 as a separate code base on the Hibernate
svn trunk. The first thing done was this org.hibernate.cache.Cache
splitting. So at this point we now have the ability to be completely
free in how we cache entity-data versus collection-data versus
query-data versus timestamps-data within the same "second level cache".
But now looking back at #1, I am no longer certain of the conclusions;
and to me the wiki did not make it clear to me what the "long term"
solution was supposed to be (nor really what the "short term" solution
is/was either). Anyone remember the specific conclusions with regards
to this point?
Re: #4 : what exactly are these differences? Now is the time to merge
Re: #5 : what about the other solution I proposed where instead of
registering synchs directly with the TC/TM, you instead delegate it to a
strategy which can route the request back through Hibernate; Hibernate
can then manage ordering the callbacks?
Re: #6 : I'm actually in favor of just moving to the new (2.0) API;
easier from a management perspective.
Ok, so my notes from the call, based on issues from the wiki
1. Multiple caches will probably only formally make it in the next
major Hibernate release - 3.3.
2 Notes on putForExternalRead() functionality, in addition to the
solution presented on the wiki:
- PFER only goes through if node does not exist; no-op otherwise
- Force asynchronous mode for replication or invalidation to prevent
- 0ms lock timeout to prevent any blocking here either. If this
fails, PFER is a no-op
- no to separate thread necessary, since we will be operating with a
0ms timeout, async replication and a no-op if the node exists. The
only real chance of any blocking here is JGroups FC which is
considered small enough a case.
3. Since JBC 1.4.1.SP1, write locks are not acquired on parents when
adding or removing children, to be more accurate to repeatable read
semantics. WLs can still be acquired on parents if enabled in the
configuration (see "LockParentForChildInsertRemove" in
which defaults to false). As such, this contention should no longer
be a problem.
4. Brian implemented for EJB3 clustering in AS 4.2, will make it's
way back into HIbernate in the 3.3 timeframe?
5. Do nothing for now since the urgency is removed. Only fails on
old versions of JBoss TS. In future (JBC 2.1 timeframe) look at what
the microcontainer has to offer with synchronisation registrations.
6. Coordination issue
7. Galder to come back with more details here, but general consensus
is not to perform transparent retries.
Feel free to add stuff I may have missed or further thoughts. Very
useful and productive call!