Hi I am working with a JBoss PojoCache (PojoCache 3.0. GA Naga, CoreCache 3.1.0 Cascabel) BUT i am using it in a WebLogic Server 10.2 with JDK 1.5 on an Solaris 64 bit Environment.
Everything is working fine !! But now we entered the stress test phase and we are running in a huge of TransactionLock Exceptions starting from

org.jboss.cache.lock.TimeoutException: read lock for /G/VALIDSHEETS/1000/M could not be acquired by Thread[[ACTIVE] ExecuteThread: '23' for queue: 'weblogic.kernel.Default (self-tuning)',5,Pooled Threads] after 50000 ms. Locks: Read lock owners: []
Write lock owner: null

java.lang.IllegalStateException: Cannot mark the transaction for rollback. xid=BEA1-10EDB1C915B28181CB68, status=Rolled back. [Reason=weblogic.transaction.internal.TimedOutException: Transaction timed out after 30 seconds

I have changed the nodeLockingScheme from mvcc to pessimistic, now the lock exceptions occurs less often but they are not gone under stress.
With stress i mean 20 concurrent users and our target is more than 100 concurrent users.

My Cache Configuration is:

<?xml version="1.0" encoding="UTF-8"?>
<jbosscache xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="urn:jboss:jbosscache-core:config:3.1">

 <!-- Configure the TransactionManager -->
 <transaction transactionManagerLookupClass="org.jboss.cache.transaction.GenericTransactionManagerLookup"/>

 <jmxStatistics enabled="false"/>

 <locking
 isolationLevel="READ_COMMITTED"
 lockParentForChildInsertRemove="false"
 lockAcquisitionTimeout="50000"
 nodeLockingScheme="pessimistic"
 writeSkewCheck="false"
 useLockStriping="true"
 concurrencyLevel="500"/>


 <eviction wakeUpInterval="5000">
 <default algorithmClass="org.jboss.cache.eviction.LRUAlgorithm" eventQueueSize="2000000">
 <property name="maxNodes" value="3000000" />
 <property name="timeToLive" value="1000000" />
 </default>

 <!-- configurations for various regions-->
 <region name="/_default_">
 <property name="maxNodes" value="3000000" />
 <property name="timeToLive" value="1000000" />
 </region>
 <region name="/G">
 <property name="maxNodes" value="500000" />
 <property name="timeToLive" value="6000000" />
 <property name="maxAge" value="6000000" />
 </region>
 <region name="/U">
 <property name="maxNodes" value="3000000" />
 <property name="timeToLive" value="3600000" />
 <property name="maxAge" value="3600000" />
 </region>
 </eviction>
</jbosscache>

Is there anything i can do avoiding these lock exceptions? Any idea?

The process of our application is the following:

The user requests data
The BusinessObjectManager looks for the data in the cache
If it can not be found in the cache the BusinessObjectManager requests the data from SAP and then attaches the data to the cache.

If the user changes the data, the cached records and the dependend ones are detached and if requested again, read from SAP and attached to the cache again.

Can anyone help?
I am really under pressure, these stress test errors will jeopardize our project.

Any help will be perfect.

Regards Edmund