Hello guys,
I've got an app running for 1.3 months now, without any problem...
Until today, just before 3PM (GMT+2) my app stopped serving all queries from
kind A.
All the other kinds (B, C, D,...) still worked.
When I looked it up in the logs, I found this error multiple times when
querying kind A.
javax.jdo.JDOFatalUserException: Application code attempted to create a
PersistenceManagerFactory named transactions-optional, but one with this
name already exists! Instances of PersistenceManagerFactory are extremely
slow to create and it is usually not necessary to create one with a given
name more than once. Instead, create a singleton and share it throughout
your code. If you really do need to create a duplicate
PersistenceManagerFactory (such as for a unittest suite), set the
appengine.orm.disable.duplicate.pmf.exception system property to avoid this
error.
The problem is obvious you say?
It would be, but I already use a Singleton. (And I searched my source
files.. I never create more than one instance!)
I'm using this code (it comes out of the JDO Google documentation):
import javax.jdo.JDOHelper;
import javax.jdo.PersistenceManagerFactory;
public final class PMF {
private static final PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-optional");
private PMF() {}
public static PersistenceManagerFactory get() {
return pmfInstance;
}
}
I did define my app as <threadsafe>true</threadsafe> so could I be a lucky
lottery winner? Meaning that the pmfInstance was set twice on exactly the
same moment? Should I put it in a synchronised block? Or should I use this
code?
public class PMF
{
private static final PersistenceManagerFactory pmfInstance =
JDOHelper.getPersistenceManagerFactory("transactions-optional");
private PMF() {}
public static PersistenceManagerFactory getInstance()
{
return pmfInstance;
}
}
But, it does not explain why I only had problems while executing queries of
kind A.. The other queries over other kinds still worked.
Unfortunately, I discovered the problem 4 hours later and the problem was
still accurate. Only disabling the app killed all running java instances and
solved my problem.
Any ideas what could have caused this?
Thnx!
Dimitri
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