Hi,
You need to ensure that you are closing the broker.
public void onEvent(){
PersistenceBroker pb =
PersistenceBrokerFactory.defaultPersistenceBroker();
pb.store(this); // or whatever it is you want to do with the broker
pb.close();
}
You should only get brokers when you need them, and close them when you've
finished with them.
HTH,
Charles.
> -----Original Message-----
> From: Michael Watson [mailto:[EMAIL PROTECTED]
> Sent: 09 October 2003 12:53
> To: OJB Users List; [EMAIL PROTECTED]
> Subject: Re: ConcurrentModificationException
>
>
> Hi Armin,
> I have an object with an init method where I assign a
> PersistenceBroker
> instance using
>
> PersistenceBrokerFactory.defaultPersistenceBroker()
>
> This object then has an onEvent() method that is called and uses
> broker.store().
>
> I tried modifying the object so that the broker is obtained
> in the onEvent
> instead of the init and I started getting
> "Borrow broker from pool failed" Exceptions. I have my
> connection-pool set
> up as follows:
>
> <connection-pool maxActive="-1" whenExhaustedAction="2"
> validationQuery="select 1 from t_client"/>
>
> Do you have any suggestions for what I might be doing wrong?
>
> Mike
>
> ----- Original Message -----
> From: "Armin Waibel" <[EMAIL PROTECTED]>
> To: "OJB Users List" <[EMAIL PROTECTED]>
> Sent: Wednesday, October 08, 2003 6:02 PM
> Subject: Re: ConcurrentModificationException
>
>
> > Hi Michael,
> >
> > On Wed, 8 Oct 2003 17:31:15 +0100, Michael Watson
> > <[EMAIL PROTECTED]> wrote:
> >
> > > Hi all,
> > >
> > > I'm finding I quite reguarly get this exception when I'm
> attempting to
> > > call
> > > PersistenceBroker.store(Object) from multiple threads
> simultaneously.
> > >
> > Do several threads share the same PB instance?
> > If so, this is not allowed. PB instances are not
> > threadsafe itself, but they are pooled so it's no
> > performance impact to use a separate PB instance for each thread.
> >
> > regards,
> > Armin
> >
> > > <?xml version='1.0'?>
> > > <exception>
> > > <cause>
> > > <detailMessage/>
> > >
> <exceptionClass>java.util.ConcurrentModificationException</exc
> eptionClass>
> > > <stackTrace>
> > >
> <stackTrace>java.util.AbstractList$Itr.checkForComodification(
> AbstractList.j
> > > ava:444)</stackTrace>
> > >
> <stackTrace>java.util.AbstractList$Itr.next(AbstractList.java:
> 417)</stackTra
> > > ce>
> > >
> <stackTrace>java.util.AbstractCollection.remove(AbstractCollec
> tion.java:250)
> > > </stackTrace>
> > >
> <stackTrace>org.apache.ojb.broker.core.PersistenceBrokerImpl.s
> tore(Unknown
> > > Source)</stackTrace>
> > >
> <stackTrace>org.apache.ojb.broker.core.PersistenceBrokerImpl.s
> tore(Unknown
> > > Source)</stackTrace>
> > >
> <stackTrace>org.apache.ojb.broker.core.DelegatingPersistenceBr
> oker.store(Unk
> > > nown Source)</stackTrace>
> > > ...
> > > </stackTrace>
> > > </cause>
> > > <detailMessage>Failed to update History record
> > > java.util.ConcurrentModificationException</detailMessage>
> > >
> <exceptionClass>org.apache.ojb.broker.PersistenceBrokerExcepti
> on</exceptionC
> > > lass>
> > > <stackTrace/>
> > > </exception>
> > >
> > > Obviously somewhere in the broker there's been an attempt
> to modify the
> > > structure of a list by 2 or more threads simultaneously.
> > >
> > > My question is, has anything been done to prevent this in a newer
> > > version or
> > > should I just catch these exceptions and retry the store?
> > >
> > > I'm using ojb-1.0.rc3 at the moment.
> > >
> > > Regards,
> > >
> > > Mike
> > >
> > >
> > >
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> > >
> >
> >
> >
> >
> >
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> >
>
>
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