Re: [eclipselink-users] Best practices for clearing the entity manager

[Tom Ware <tom.ware@xxxxxxxxxx>]

Hi John,

  What do you mean when you say caching is not enabled?  What settings are you 
using to disable the cache? Note that within an open entity manager there will 
always be a cache of the objects that are managed within that entity manager.

  Rarely does disabling the cache actually achieve what you want it to since 
the cache is also used to maintain identity.  There are a number of options you 
can use to fine tune your cache and/or force queries to the database.

  Take a look at the following link for some caching options.  Some things that 
might be good to try are using a CacheType of WEAK, setting the cache to not be 
shared, and having it expire after a certain amount of time.

http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#Using_EclipseLink_JPA_Extensions_for_Entity_Caching

  Also have a look at our query hints.  You could specify the 
eclipselink.cache-usage hint to tell a query to avoid the cache or the 
eclipselink.refresh hint to tell the query to refresh from the database.

http://wiki.eclipse.org/Using_EclipseLink_JPA_Extensions_%28ELUG%29#How_to_Use_EclipseLink_JPA_Query_Hints

  There is also the entityManager.refresh() operation that forces objects to be 
refreshed and the entityManager.clear() operation that cleans our the individual 
entityManager.

-Tom


John Ament wrote:
> Hey everyone
>
> So I've begun to notice that there's some odd behavior in eclipse link 
> when it comes to a multiple server environment that's not cluster (e.g. 
> 4 instances of glassfish running on 2 servers).  Basically, it looks 
> like repeated calls to em.find as well as execution of queries returns 
> the same data rather than actually running the queries against the 
> database.  Does anyone have any tips on how to avoid issues like this?  
> Caching is not enabled.
>
> Thanks,
>
> John
>
>
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