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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
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:[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.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:[EMAIL PROTECTED]
P.S. A good JDO? O, Gasp!
