Re: AW: Forgot subject: Strange Could not locate metadata for the classError?

[Marc Prud'hommeaux]

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:[EMAIL PROTECTED] 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.getClassMetaDat 
a(
JPQLExpressionBuilder.java:164)
        at
org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.resolveClassMet 
aD
ata(JPQLExpressionBuilder.java:142)
        at
org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateMet 
aD
ata(JPQLExpressionBuilder.java:211)
        at
org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateMet 
aD
ata(JPQLExpressionBuilder.java:181)
        at
org.apache.openjpa.kernel.jpql.JPQLExpressionBuilder.getCandidateTyp 
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.populateFromCompilati 
on
(ExpressionStoreQuery.java:145)
        at
org.apache.openjpa.datacache.QueryCacheStoreQuery.populateFromCompil 
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.createNamedQuery
(EntityManagerImpl.java:785)
        at
org.apache.openjpa.persistence.EntityManagerImpl.createNamedQuery
(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