Re: [eclipselink-users] Performance questions EclipseLink vs. Hibernate

["Tim Hollosy" <hollosyt@xxxxxxxxx>]

To expand on the memory error that heap size error occurs when you run
out of space used to instantiate new classes, so add -Xmx<maximum heap
size> to the command line to allocate more space.

On Mon, May 26, 2008 at 9:29 AM, James Sutherland <jamesssss@xxxxxxxxx> wrote:
> Your memory error could mean you are pretty low on memory in general, and
> are barely scraping through in either cases, and should try increasing your
> JVM memory size.  Otherwise something really un-usual could be occurring
> cause the memory issue.  This would be more difficult to determine, perhaps
> include more information on the Product object.
>
>
>
> Leon Derks-2 wrote:
>>
>> Hello James,
>>
>> db = oracle xe 10.2.0
>> os= win xp
>> jvm = Java 6
>> server tomcat 6.16
>> jdbc = Oracle JDBC Driver version - "10.2.0.3.0"
>>
>> I don't use <property name="persistence.tools.weaving" value="true"> or
>> static weaving.
>> But why is this needed? What is the difference?
>> Are objects not lazy loaded when no weaving is enabled, but is the full
>> object graph loaded? Does weaving also influence performance when
>> persisting objects?
>>
>> I have added the property: <property
>> name="eclipselink.jdbc.batch-writing" value="Oracle-JDBC"/>in
>> But noticed no performance difference. I'm still getting a
>> "java.lang.OutOfMemoryError: Java heap space".
>>
>> I have not a security manager set in my JVM. I use a default jvm without
>> configurations.
>>
>> In my persisting case, I'm looping through a List of entities and
>> persist them one by one.
>> After the loop I try to commit the transaction, but get a
>> "java.lang.OutOfMemoryError: Java heap space".
>> Like this
>>
>> importedData = (Import) unmarshaller.unmarshal("huge xml file of size
>> 10-50MB")
>> entityManager.getTransaction().begin();
>> for(Product product : importedData.getProducts) {
>>     //product is a deep object graph with objects.
>>     entityManager.persist(product);
>> }
>> entityManager.getTransaction().commit();
>>
>> The strange thing is that it works with hibernate.
>>
>> Leon
>>
>>
>>
>> James Sutherland wrote:
>>> This is very very odd, in our extensive performance testing we have done
>>> comparing with Hibernate we have greatly exceed their performance is
>>> almost
>>> every possible usecase we have tested.  Could you please include more
>>> details on exactly what your test is doing and exactly what your
>>> environment
>>> is (db, os, jvm, server, jdbc).
>>>
>>> My guess is you issue is related one of the following,
>>> 1 - You do not have weaving enabled in EclipseLink.  EclipseLink requires
>>> this to do lazy loading and change tracking.  You must enable weaving
>>> either
>>> through the agent, or static weaver.
>>> 2 - If using Oracle Hibernate enabled batch writing by default, where as
>>> you
>>> must turn in on in EclipseLink through a persistence property.
>>> 3 - Do you have a security manager set in your jvm?  There is a setting
>>> you
>>> need to set currently for this in EclipseLink.
>>>
>>>
>>>
>>>
>>> Leon Derks-2 wrote:
>>>
>>>> Hello,
>>>>
>>>> Today we noticed differences in performance between EclipseLink and
>>>> Hibernate.
>>>>
>>>> We had made up a test case with a big list of objects(Entities). Each
>>>> Enitity has references to other Entities / list of Entities.
>>>> Some of these Entities are shared and others are new.
>>>>
>>>> To save one Entity from the main list took about 780 milliseconds to
>>>> persist the whole Object graph into the db.
>>>> There was not much difference between EclipseLink and Hibernate in this
>>>> case.
>>>>
>>>> But when we iterated through the big list of entities and persisted them
>>>> one by one, there was a big difference between EclipseLink and
>>>> Hibernate.
>>>> We tried one transaction for the whole list and also a single
>>>> transaction per Entity in the list.
>>>>
>>>> Hibernate succeeded in every case and was much faster then EclipseLink
>>>> (sometimes 50% faster).
>>>> EclipseLink only succeeded when saving one Entity per transaction,
>>>> during the other cases (saving the whole list of objects in one
>>>> transaction) we did get "java.lang.OutOfMemoryError: Java heap space".
>>>> EclipseLink used almost 15 minutes to complete and Hibernate did the
>>>> same in 9 minutes.
>>>>
>>>> Based on our results we would go for Hibernate at the moment. But are
>>>> there ways to speed up performance in EclipseLink?
>>>> Why is there so much difference in performance between Hibernate and
>>>> EclipseLink.
>>>>
>>>> Leon
>>
>
>
> -----
> ---
> http://wiki.eclipse.org/User:James.sutherland.oracle.com James Sutherland
> http://www.eclipse.org/eclipselink/
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> TopLink
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> http://wiki.oracle.com/page/TopLink TopLink
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> http://www.nabble.com/EclipseLink-f26430.html EclipseLink
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> --
> View this message in context: http://www.nabble.com/Performance-questions-EclipseLink-vs.-Hibernate-tp16768260p17471973.html
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