intershop ORMException could not update - refresh ORMObject

问题

In a clustered intershop environment, we see a lot of error messages. I'm suspecting the communication between the application servers is not reliable.

Caused by: com.intershop.beehive.orm.capi.common.ORMException: 
Could not UPDATE object: com.intershop.beehive.bts.internal.orderprocess.basket.BasketPO

Is there safe way to for the local application server, to load the latest instance.

   BasketPO basket = null;
        try{
            BasketPOFactory factory = (BasketPOFactory) NamingMgr.getInstance().lookupFactory(BasketPOFactory.FACTORY_NAME);
            try(ORMObjectCollection<BasketPO>baskets = factory.getObjectsBySQLWhere("uuid=?", new Object[]{basketID},CacheMode.NO_CACHING);){
                if(null != baskets && !baskets.isEmpty()){
                    basket = baskets.stream().findFirst().get();
                }
            }
        }
        catch(Throwable t){
            Logger.error(this, t.getMessage(),t);
        }

Does the ORMObject#refresh method help ?

    try{
        if(null != basket)
              basket.refresh();
    }
    catch(Throwable t){
        Logger.error(this, t.getMessage(),t);
    }

回答1:

You experience that error because an optimistic lock "fails". To understand the problem better I'll try to explain how the optimistic locking works in particular in the Intershop ORM layer.

There is a column named OCA in the PO tables (OCA == optimistic control attribute?). Imagine that two servers (or two different threads/transactions) try to update the same row in a table. For performance reasons there is no DB locking involved by default (e.g. by issuing select for update). Instead the first thread/server increments the OCA by one when it updates the row successfully within its transaction.

The second thread/server knows the value of the OCA from the time that it created its own state. It then tries to update the row by issuing a similar query:

UPDATE ... OCA = OCA + 1 ... WHERE UUID = <uuid> AND OCA = <old_oca>

Since the OCA is already incremented by the first thread/server this update fails (in reality - updates 0 rows) and the exception that you posted above is thrown when the ORM layer detects that no rows were updated.

Your problem is not the inter-server communication but rather the fact that either:

multiple servers/threads try to update the same object;
there are direct updates in the database that bypass the ORM layer (less likely);

To solve this you may:

Avoid that situation altogether (highly recommended by me :-) );
Use the ISH locking framework (very cumbersome imHo);
Use pesimistic locking supported by the ISH ORM layer and Oracle (beware of potential performance issues, deadlocks, bugs);
Use Java locking - but since the servers run in different JVM-s this is rarely an option;

OFFTOPIC remarks: I'm not sure why you use getObjectsBySQLWhere when you know the primary key (uuid). As far as I remember ORMObjectCollection-s should be closed if not iterated completely.

UPDATE: If the cluster is not configured correctly and the multicasts can't be received from the nodes you won't be able to resolve the problems programatically.

回答2:

The "ORMObject.refresh()" marks the cached shared state as invalid. Next access to the object reloads the state from the database. This impacts the performance and increase the database server load.

BUT: The "refresh()" method does not reload the PO instance state if it already assigned to the current transaction.

Would be best to investigate and fix the server communication issues.

回答3:

Other possibility is that it isn't a communication problem (multicast between node in the cluster i assume), but that there are simply two request trying to update the basket at the same time. Example two ajax request to update something on the basket.

I would avoid trying to "fix" the orm, it would only cause more harm than good. Rather investigate further and post back more information.

来源：https://stackoverflow.com/questions/45580096/intershop-ormexception-could-not-update-refresh-ormobject

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intershop