[jbosscache-dev] LockParentForChildInsertRemove and PessimisticLocking

[Brian Stansberry]

Continuing dialogue with myself. :)

I've found the logic in PessimisticNodeBasedLockManager where the
LockParentForChildInsertRemove configuration is meant to be coming 
through via the Node. In our testing we're seeing cases where write 
locks are being acquired on parent nodes, which isn't the intent. I'll 
dig further.

Brian Stansberry wrote:
> https://jira.jboss.org/jira/browse/JBCACHE-1527
> 
> Brian Stansberry wrote:
>>  From looking at the JBC 3 code, it seems the 
>> LockParentForChildInsertRemove configuration is no longer respected for 
>> pessimistic locking.  I can't trace any path from the property in 
>> Configuration to code that uses it. 
>> PessimisticLockInterceptor.handlePutCommand, handleMoveCommand and 
>> handleRemoveNodeCommand all always tell the lock manager to lock 
>> parents. handleEvictFqnCommand always tells the lock manager not to lock 
>> parents.
>>
>> This is causing failures in buddy replication testing when nodes 
>> join/leave clusters under load. There's a lot of data gravitation plus 
>> stuff like migrating defunct backup trees to "DEAD" regions. Too much 
>> contention for parent level locks.
>>
>> Plus locking on the structural parent to add/remove session nodes will 
>> suck for the session caching use case.
>>
> 
> 


-- 
Brian Stansberry
Lead, AS Clustering
JBoss by Red Hat