Hi. I had the same problem with deleteCollections. A defensive copy must
be done by OJB before returning the collection to the user in that case.
In your case I'm not sure what it is !
Here is the patch that solves my problem,Maybe you can try to fix your
problem based on this patch !
On Thu, 2003-10-16 at 14:07, R�da Benzair wrote:
> Hi All
>
> It seems OJB has a multi thread unsafe behaviour when handling M:N
> relations:
>
> java.util.ConcurrentModificationException
> at java.util.HashMap$HashIterator.nextEntry(HashMap.java:762)
> at java.util.HashMap$KeyIterator.next(HashMap.java:798)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.deleteMtoNImplementor(P
> ersistenceBrokerImpl.java:970)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeCollections(Persis
> tenceBrokerImpl.java:785)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeToDb(PersistenceBr
> okerImpl.java:2007)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:1889)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:665)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeReferences(Persist
> enceBrokerImpl.java:692)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeToDb(PersistenceBr
> okerImpl.java:1954)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:1889)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:665)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeReferences(Persist
> enceBrokerImpl.java:692)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.storeToDb(PersistenceBr
> okerImpl.java:1954)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:1889)
> at
> org.apache.ojb.broker.core.PersistenceBrokerImpl.store(PersistenceBroker
> Impl.java:665)
> at
> org.apache.ojb.broker.core.DelegatingPersistenceBroker.store(DelegatingP
> ersistenceBroker.java:160)
> at
> org.apache.ojb.broker.core.DelegatingPersistenceBroker.store(DelegatingP
> ersistenceBroker.java:160)
>
> Replacing the use of an HashMap -unsynchro- with an Hashtable
> -synchronized- would solve the problem, wouldn't it?
>
> This is a trouble that happens on a production system and i'm looking
> foward to hear about your response!
>
> Thanks in advance!
>
>
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--
Leandro Rodrigo Saad Cruz
IT - Inter Business Tecnologia e Servicos (IB)
http://www.ibnetwork.com.br
http://db.apache.org/ojb
http://xingu.sourceforge.net
Index: src/java/org/apache/ojb/broker/core/PersistenceBrokerImpl.java
===================================================================
RCS file: /home/cvspublic/db-ojb/src/java/org/apache/ojb/broker/core/PersistenceBrokerImpl.java,v
retrieving revision 1.38
diff -u -b -B -r1.38 PersistenceBrokerImpl.java
--- src/java/org/apache/ojb/broker/core/PersistenceBrokerImpl.java 15 Oct 2003 15:41:10 -0000 1.38
+++ src/java/org/apache/ojb/broker/core/PersistenceBrokerImpl.java 16 Oct 2003 18:33:36 -0000
@@ -588,14 +588,25 @@
Object col = cds.getPersistentField().get(obj);
if (col != null)
{
-
+ System.out.println("collection type : " + col.getClass().getName());
if (col instanceof ManageableCollection)
{
- colIterator = ((ManageableCollection) col).ojbIterator();
+ System.out.println("Duplicating collection");
+
+ ManageableCollection original = (ManageableCollection) col;
+ ManageableCollection copy = new RemovalAwareCollection();
+ copy.ojbAddAll(original);
+ colIterator = copy.ojbIterator();
+// colIterator = ((ManageableCollection) col).ojbIterator();
}
else if (col instanceof Collection)
{
- colIterator = ((Collection) col).iterator();
+ System.out.println("Duplicating collection");
+ //LEANDRO: make a defensive copy to prevent ConcurrentModificationException
+ Collection original = (Collection) col;
+ Collection copy =new ArrayList(original.size());
+ copy.addAll(original);
+ colIterator = copy.iterator();
}
else if (col.getClass().isArray())
{
@@ -1072,6 +1083,7 @@
*/
private void retrieveReference(Object obj, ClassDescriptor cld, ObjectReferenceDescriptor rds, boolean forced, HashMap retrievalTasks)
{
+ logger.debug("RETRIEVING reference for["+cld.getClassNameOfObject()+"] on field ["+rds.getAttributeName()+"]");
PersistentField refField;
Object refObj;
if (forced || rds.getCascadeRetrieve())
@@ -1104,6 +1116,7 @@
*/
private void retrieveCollection(Object obj, ClassDescriptor cld, CollectionDescriptor cds, boolean forced, HashMap retrievalTasks)
{
+ logger.debug("RETRIEVING collection for["+cld.getClassNameOfObject()+"] on field ["+cds.getAttributeName()+"]");
if (forced || cds.getCascadeRetrieve())
{
if ((retrievalTasks != null) && !cds.isLazy() && !cds.isMtoNRelation()
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