Hibernate version: 3.0
Name and version of the database you are using: MySQL 5.0

Hi,

I want to run my application in a clustered environment, and was wondering how Hibernate cache will behave in this case.

Suppose there are two application servers A and B. If Hibernate puts some data in its cache on server A, and the same data is modified using server B, then how will Hibernate know of this change in Server A ? This way application can serve stale content.

Is there a way to avoid the above problem without loosing much performance ?

Thanks in Advance
Varun

Hi,

I think that data stored in Hibernate session is only visible within same VM by default. If you want to have shared cache, you'll need to get something like Tangosol Coherence and configure Hibernate to use that. Otherwise data loaded into session in cluster A will be separate from data loaded into session in cluster B.
If you need to somehow restrict access to given rows in db you could use lock for update (in Hibernate session). Or get a distributed cache product like Tangosol.

HTH,

Bratek

Both ehcache and JBoss TreeCache are clusterable. You just need to use one of them as your second-level cache provider in Hibernate, and configure them properly for your cluster. You don't need Tangosol.

http://www.hibernate.org/hib_docs/v3/reference/en/html/performance.html#performance-cache

Note that link does not list ehcache as being cluster-safe, but it has had this capability for awhile now and is considered stable - http://ehcache.sourceforge.net/

Note that I am talking about the Hibernate's second-level cache here, not a given Hibernate Session, which is what bratek seemed to refer to. But I think this is what you are after.

You might also want to look at our GigaSpaces - Hibernate plug-in.

More info here: http://www.gigaspaces.com/wiki/display/ ... che+Plugin

And here: http://hibernate.org/201.html.

I think using Tangosol, ehcache or gigaspaces will solve the problem of second-level cache in a clustered environment. But, I also have one more problem.

I have a second application which can modify the same datastore as the second application. Both uses Hibernate's second-level cache. How to synchronise cache in this case ? Do, I have to write my own CacheProvider to handle this ? If yes, then can somebody point a good reference to do so.

Thanks in Advance
Varun

Iam not very sure if it will work, but if both your applications are using "Hibernate" and the "same second-level caching" mechanism to access the datastore, then you could configure your cache to sync all the clustered caches through the configuration file. Jbosscache is a good clustered cache option too.