Re: [eclipselink-users] Out of memory while commiting large uow

[James Sutherland <jamesssss@xxxxxxxxx>]

In JPA and EclipseLink you can use clear() for this.

Calling clear() after calling flush() will free the registered objects and
memory.

There is a persistence.xml option "eclipselink.flush-clear.cache" that lets
you configure what occurs on a clear() called after a flush().  By default
any modified objects will be invalidated in the shared cache.



Tabi wrote:
> 
> Hello, we encounter this problem for years on TopLink then there is not in
> Hibernate.
> 
> The problem is that Toplink awaits the uow.commit () before merging
> changes in the cache objects and before release work objects (backup and
> clone).
> 
> If a transaction modify 10.000 objects, TopLink references 30.000 objects
> (10.000 refCache, 10.000 clone, 10.000 backup). The 30.000 objects will be
> released once the database commit completed and the merge completed in
> memory.
> 
> We want Toplink offers an option to make several Flush in unitOfWork, each
> flush will send SQL to database (insert, update, delete) without sql
> commit then mark flushed Objects as invalid before releasing them so that
> the garbage collector can garbage flushed objects.
> 
> Example:
> 
> uow.begin(); / * begin of transaction on 10.000 objects * /
> application modify first 1.000 objects (from 1 to 1.000)
> uow.flush () / * Toplink send sql to database, toplink flag 1.000 as
> invalid, Toplink release 1.000 objects to the GC * /
> 
> application modify next 1000 objects (from 1.001 to 2.000)
> uow.flush () / * Toplink send sql to database, toplink flag 1.000 as
> invalid, Toplink release 1.000 objects to the GC * /
> ....
> 
> application modify last 1000 objects objects (9001 .. 10000)
> uow.flush () / * Toplink send sql to database, toplink flag 1.000 as
> invalid, Toplink release 1.000 objects to the GC * /
> 
> uow.commit(); / * Toplink send sql-commit to database, no objects to
> release to GC* /
> 
> Can you tell me if you intend to implement this function because we need
> long running transaction process without outOfMemory suffer?
> 
> Thank you for your help
> Regards
> Tabi
> 


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http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland 
http://www.eclipse.org/eclipselink/
 EclipseLink ,  http://www.oracle.com/technology/products/ias/toplink/
TopLink 
Wiki:  http://wiki.eclipse.org/EclipseLink EclipseLink , 
http://wiki.oracle.com/page/TopLink TopLink 
Forums:  http://forums.oracle.com/forums/forum.jspa?forumID=48 TopLink , 
http://www.nabble.com/EclipseLink-f26430.html EclipseLink 
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