[jboss-user] [JBossCache] - Re: NPE when using optimistic locking with JbossCache 1.4.0.

manik.surtani@jboss.com do-not-reply at jboss.com
Tue Jan 9 09:59:45 EST 2007

What you see is a validation error due to concurrent writes.  This will occasionally happen when using optimistic locking.

This is caused when:

1) Thread1 starts tx
2) Thread1 copies data to workspace
3) Thread2 starts tx 
4) Thread2 copies data to workspace
5) Thread2 updates data 
6) Thread2 commits
7) Thread1 updates data
8) Thread1 commits - FAILS.  

Step 8 fails because the data that Thread1 has is stale since Thread2 has updated it.  This is the version mismatch that you see.

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