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From Marc Prud'hommeaux <mprud...@apache.org>
Subject Re: AW: AW: Forgot subject: Strange Could not locate metadata for the classError?
Date Sat, 24 Mar 2007 07:58:29 GMT
Hans-

> If I understand it right - above lookup code will ensure that there  
> is only
> a single EM within a JTA transaction even if I call the method  
> several times
> from several methods within the TX.

Yes, it should. You might want to print out the  
System.identityHashCode(broker) to be sure, but it looks like this  
will replicate the transaction association logic that we perform  
automatically in a JEE5 environment.

> So does the requirement to set the "multithreaded" property remain  
> by this
> usage scenario?

No, not so long as a single Broker is ever used by a single thread  
(which should be the case as long as the same JTA transaction is not  
used from multiple threads).




On Mar 24, 2007, at 12:45 AM, Hans J. Prueller wrote:

> I'm not sure if all of you know, but we are utilizing OpenJPA within a
> J2EE1.4 container for EJB3 migration purposes. In this "special"  
> case we
> are using JPA in "application managed" mode but with synchronized JTA
> transactions of the container.
>
> the current implementation holds a single EMF as a static member in  
> memory
> for the whole JVM (there is definitely only 1 VM currently running)  
> and
> every SLSB method called starts with creating a new  
> EntityManager ... here
> is a code I think Patrick suggested to ensure synchronization of  
> the EM
> with the JTA tx of the container:
>
> final BrokerFactory bf = OpenJPAPersistence.toBrokerFactory(emf);
>
> // the broker is part of a  JTA  managed tx
> //	 look for an existing Broker on the tx
> final Broker b = bf.newBroker(bf.getConfiguration()
> 			.getConnectionUserName(), bf.getConfiguration()
> 			.getConnectionPassword(), true,
> bf.getConfiguration().getConnectionRetainModeConstant(), true);
>
> // do some JPA configuration setup. Logic stolen from
> // EntityManagerFactoryImpl.
> b.setAutoDetach(AutoDetach.DETACH_CLOSE, true);
> b.setAutoDetach(AutoDetach.DETACH_ROLLBACK, true);
> b.setDetachedNew(false);
>
> return OpenJPAPersistence.toEntityManager(b);
>
>
> If I understand it right - above lookup code will ensure that there  
> is only
> a single EM within a JTA transaction even if I call the method  
> several times
> from several methods within the TX.
>
> So does the requirement to set the "multithreaded" property remain  
> by this
> usage scenario?
>
> Hans
>
>> -----Ursprüngliche Nachricht-----
>> Von: Craig.Russell@Sun.COM [mailto:Craig.Russell@Sun.COM]
>> Gesendet: Freitag, 23. März 2007 23:46
>> An: open-jpa-dev@incubator.apache.org
>> Betreff: Re: AW: Forgot subject: Strange Could not locate metadata  
>> for the
>> classError?
>>
>>>>> Marc Prud'hommeaux wrote:
>>>>>
>>>>>> Hans-
>>>>>> I don't see how the error could be data-related.
>>>>>> One thing: if you are using the same EMF from multiple threads,
>>>>>> do  you have the "openjpa.Multithreaded" property explicitly
>>>>>> set  to  "true" in your persistence.xml (or however you are
>>>>>> configuring  the  EMF)?
>>
>>
>> Just to make sure there is no confusion. What I think Marc meant was
>> "using the same EM from multiple threads". The openjpa.Multithreading
>> property should not apply to multiple threads accessing the
>> EntityManagerFactory, which is always thread-safe. The property
>> should refer to multiple threads accessing the same EntityManager,
>> which is not thread-safe by default.
>>
>> Craig
>>
>> On Mar 23, 2007, at 2:56 PM, Marina Vatkina wrote:
>>
>>> Marc,
>>>
>>> No, in GlassFish (GF) it shouldn't be the case, but there could be
>>> more than 1 EMF created at the same time. The test case uses
>>> stateless session bean for accessing EM, so there is no guarantee
>>> that the same bean instance serves the 1st method (with a
>>> successful persist) and the 2nd (with a failed query). But what's
>>> worth noting, that in both cases, mine and Hans's it's the query
>>> that causes the problems).
>>>
>>> BTW, I need to test again without tracing - it can slow things down
>>> and hide the problem.
>>>
>>> regards,
>>> -marina
>>>
>>> Marc Prud'hommeaux wrote:
>>>> Marina-
>>>> In a normal J2EE app, the same EntityManager will never be used
>>>> concurrently from multiple threads. That might also be the case
>>>> in  your environment, but it would be interesting to see if the
>>>> problem  ever crops up after you enable this property.
>>>> On Mar 23, 2007, at 2:36 PM, Marina Vatkina wrote:
>>>>> Marc,
>>>>>
>>>>> Does OpenJPA figures out by itself that it is running in a
>>>>> multithreaded environment when used in an app- or web-server? Or
>>>>> do  you expect users to always specify this setting when they
>>>>> decide to  deploy it to a multi-threaded container?
>>>>>
>>>>> thanks,
>>>>> -marina
>>>>>
>>>>> Marc Prud'hommeaux wrote:
>>>>>
>>>>>> Hans-
>>>>>> I don't see how the error could be data-related.
>>>>>> One thing: if you are using the same EMF from multiple threads,
>>>>>> do  you have the "openjpa.Multithreaded" property explicitly
>>>>>> set  to  "true" in your persistence.xml (or however you are
>>>>>> configuring  the  EMF)? Failure to do this means that access to
>>>>>> the broker is   unsynchronized, and I can see how it might lead
>>>>>> to a problem like  this.
>>>>>> On Mar 23, 2007, at 11:46 AM, Hans J. Prueller wrote:
>>>>>>
>>>>>>> hm.. sounds strange. could it bet he case that the error
>>>>>>> message   openjpa is
>>>>>>> printing is only a subsequent error of another one below/before?
>>>>>>>
>>>>>>> as the JNDI binding did not really work (as you can remember:
>>>>>>> everytime I am
>>>>>>> accessing the EMF from JNDI it is initialized again and again)
>>>>>>> so  I  did a
>>>>>>> quick-and-dirty solution for the PoC of OpenJPA integration:
>>>>>>> I   saved the EMF
>>>>>>> as a static field instead to JNDI, i.e. the first time it is
>>>>>>> accessed it is
>>>>>>> created - then every client throughout my app should access
>>>>>>> the   same static
>>>>>>> EMF instance. As there is definitely only a single JVM this
>>>>>>> shouldn't make
>>>>>>> problems I suggest...
>>>>>>>
>>>>>>> Additionally I did not see any data in the logs that is
>>>>>>> indicating  that a
>>>>>>> second EMF is initialized or sth. like that. The strange thing
>>>>>>> is  that it
>>>>>>> worked several invocations before and after .. could it be a
>>>>>>> data- related
>>>>>>> problem? Anyway, I was not able to reproduce the error....
>>>>>>>
>>>>>>> Hans
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> -----Ursprüngliche Nachricht-----
>>>>>>>> Von: Marc Prud'hommeaux [mailto:mprudhomapache@gmail.com]
Im
>>>>>>>> Auftrag von
>>>>>>>> Marc Prud'hommeaux
>>>>>>>> Gesendet: Freitag, 23. März 2007 17:59
>>>>>>>> An: open-jpa-dev@incubator.apache.org
>>>>>>>> Betreff: Re: Forgot subject: Strange Could not locate
>>>>>>>> metadata  for  the
>>>>>>>> classError?
>>>>>>>>
>>>>>>>> Hans-
>>>>>>>>
>>>>>>>> There are only two possible conditions in which I can see
this
>>>>>>>> problem happening:
>>>>>>>>
>>>>>>>> 1. the class "com.lbslogics.ims.model.PositionLog" is not
>>>>>>>> loadable in
>>>>>>>> the current environment's classloader.
>>>>>>>> 2. the PositionLog class was registered with the
>>>>>>>> MetaDataRepository
>>>>>>>> during the lookup process.
>>>>>>>>
>>>>>>>> Since the same code has been executed hundreds of times via
>>>>>>>> the MDB
>>>>>>>> prior to this error, neither of these seems very plausible.
>>>>>>>> Are you
>>>>>>>> sure that the exact same EntityManagerFactory (in the same
>>>>>>>> JVM) has
>>>>>>>> been used prior to this error to execute the same method?
The
>>>>>>>> fact
>>>>>>>> that it looks like we are parsing the query for the first
>>>>>>>> time  (since
>>>>>>>> it appears we are making a new internal parse compilation
from
>>>>>>>> it)
>>>>>>>> makes it look like that particular method has not yet been
>>>>>>>> called for
>>>>>>>> that EntityManager's EntityManagerFactory.
>>>>>>>>
>>>>>>>> If this is something you can reproduce, it would be
>>>>>>>> interesting  if we
>>>>>>>> could see more logging output (enabled by setting the  
>>>>>>>> "kodo.Log"
>>>>>>>> property to "DefaultLevel=TRACE"), especially those messages
>>>>>>>> that are
>>>>>>>> on the MetaData channel.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>> On Mar 23, 2007, at 5:57 AM, Hans J. Prueller wrote:
>>>>>>>>
>>>>>>>>> full stack trace (up until application specific stuff)
is:
>>>>>>>>>
>>>>>>>>> 2007-03-22 21:34:53,287 : SEVERE : WorkThread-2/34 :
>>>>>>>>> Logger.log :
>>>>>>>>> system exception in business method:
>>>>>>>>> <4|true|0.9.7-incubating-SNAPSHOT>
>>>>>>>>> org.apache.openjpa.persistence.ArgumentException: Could
not
>>>>>>>>> locate
>>>>>>>>> metadata for the class using alias "PositionLog". Registered
>>>>>>>>> alias
>>>>>>>>> mappings: "{PositionLog=[class
>>>>>>>>> com.lbslogics.ims.model.PositionLog]}"
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.meta.MetaDataRepository.getMetaData
>>>>>>>>> (MetaDataRepository.java:345)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getClassM

>>>>>>>>> et
>>>>>>>>> aD at a(
>>>>>>>>> JPQLExpressionBuilder.java:164)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.resolveCl

>>>>>>>>> as
>>>>>>>>> sM et aD
>>>>>>>>> ata(JPQLExpressionBuilder.java:142)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandid

>>>>>>>>> at
>>>>>>>>> eM et aD
>>>>>>>>> ata(JPQLExpressionBuilder.java:211)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandid

>>>>>>>>> at
>>>>>>>>> eM et aD
>>>>>>>>> ata(JPQLExpressionBuilder.java:181)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandid

>>>>>>>>> at
>>>>>>>>> eT yp e(
>>>>>>>>> JPQLExpressionBuilder.java:174)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.access
>>>>>>>>> $500(JPQLExpressionBuilder.java:61)
>>>>>>>>>     at org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder
>>>>>>>>> $ParsedJPQL.populate(JPQLExpressionBuilder.java:1668)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.jpql.JPQLParser.populate
>>>>>>>>> (JPQLParser.java:52)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.ExpressionStoreQuery.populateFromCom

>>>>>>>>> pi
>>>>>>>>> la ti on
>>>>>>>>> (ExpressionStoreQuery.java:145)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.datacache.QueryCacheStoreQuery.populateFrom

>>>>>>>>> Co
>>>>>>>>> mp il at
>>>>>>>>> ion(QueryCacheStoreQuery.java:237)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.QueryImpl.newCompilation
>>>>>>>>> (QueryImpl.java: 644)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.QueryImpl.compilationFromCache
>>>>>>>>> (QueryImpl.java:625)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.QueryImpl.compileForCompilation
>>>>>>>>> (QueryImpl.java:591)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.kernel.QueryImpl.compileForExecutor
>>>>>>>>> (QueryImpl.java:653)
>>>>>>>>>     at org.apache.openjpa.kernel.QueryImpl.compile
>>>>>>>>> (QueryImpl.java:560)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.persistence.EntityManagerImpl.createNamedQu

>>>>>>>>> er
>>>>>>>>> y
>>>>>>>>> (EntityManagerImpl.java:785)
>>>>>>>>>     at
>>>>>>>>> org.apache.openjpa.persistence.EntityManagerImpl.createNamedQu

>>>>>>>>> er
>>>>>>>>> y
>>>>>>>>> (EntityManagerImpl.java:62)
>>>>>>>>>     at
>>>>>>>>
>>>>>>>>
>>>>>>>> com.lbslogics.ims.model.PositionLog.findById(PositionLog.java:
>>>>>>>> 175)
>>>>>>>>
>>>>>>>>>     at
>>>>>>>>> com.lbslogics.ims.persistence.ejb.EventBean.getPositionLog
>>>>>>>>> (EventBean.java:2875)
>>>>>>>>>          [ ... some more ]
>>>>>>>>>
>>>>>>>>> The corresponding EventBean is a SLSB (EJB2.1) and the
>>>>>>>>> method  looks
>>>>>>>>> like
>>>>>>>>> that:
>>>>>>>>>
>>>>>>>>>         /**
>>>>>>>>>      *
>>>>>>>>>      * @return
>>>>>>>>>      */
>>>>>>>>>     public PositionLog getPositionLog(final EntityManager
 
>>>>>>>>> em) {
>>>>>>>>>         final PositionLog log = PositionLog.findById(em,
>>>>>>>>
>>>>>>>>
>>>>>>>> getPositionLogId
>>>>>>>>
>>>>>>>>> ());
>>>>>>>>>         return log;
>>>>>>>>>     }
>>>>>>>>>
>>>>>>>>> and the Positionlog.findById is a static method which
>>>>>>>>> encapsulates
>>>>>>>>> some
>>>>>>>>> of the "technical work":
>>>>>>>>>
>>>>>>>>>         public static PositionLog findById(EntityManager
em,
>>>>>>>>> Long
>>>>>>>>> plId)
>>>>>>>>> {
>>>>>>>>>         Query q = em.createNamedQuery("PositionLog.byId");
>>>>>>>>>         q.setParameter("id", plId);
>>>>>>>>>
>>>>>>>>>         try {
>>>>>>>>>             return (PositionLog) q.getSingleResult();
>>>>>>>>>         } catch (javax.persistence.NoResultException
e) {
>>>>>>>>>             logger.finest("findById: did not find result
for
>>>>>>>
>>>>>>>
>>>>>>> id=" +
>>>>>>>
>>>>>>>> plId);
>>>>>>>>
>>>>>>>>>             return null;
>>>>>>>>>         }
>>>>>>>>>     }
>>>>>>>>>
>>>>>>>>> This method or better the top-level entry point of this
>>>>>>>>> method is
>>>>>>>>> called
>>>>>>>>> several hundred times for different records, all invoked
by a
>>>>>>>>> MDB.
>>>>>>>>> Could
>>>>>>>>> it be some concurrency issue because after several hundred
>>>>>>>>> invocations
>>>>>>>>> only a single exception occured?
>>>>>>>>>
>>>>>>>>> Hans
>>>>>>>>>
>>>>>>>>> Am Freitag, den 23.03.2007, 05:48 -0700 schrieb Patrick
 
>>>>>>>>> Linskey:
>>>>>>>>>
>>>>>>>>>> Could you post the full stack trace, and maybe some
code
>>>>>>>>>> showing  how
>>>>>>>>>> you're invoking the JPA APIs?
>>>>>>>>>>
>>>>>>>>>> -Patrick
>>>>>>>>>>
>>>>>>>
>>>>>
>>>
>>
>> Craig Russell
>> Architect, Sun Java Enterprise System http://java.sun.com/products/ 
>> jdo
>> 408 276-5638 mailto:Craig.Russell@sun.com
>> P.S. A good JDO? O, Gasp!
>
>


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