[jboss-user] [JBoss jBPM] - Re: Update of the root token after one of the sub-tokens in

[clandestino_bgd]

Hi, I am facing StaleObjectExceptions with heavy load in the following scenario.

- Dynamic Fork (N child tokens are created)
- For each child token there is a State and and task node  
- Each State has an action handler on node-enter event which calls async WS. When WS operation is finished, the callback is made (token is signalled). 

Note: No node or action handler is declared as async or exclusive.
Exception: 

  | org.hibernate.StaleObjectStateException: Row was updated or deleted by another transaction (or unsaved-value mapping was incorrect): 
  | [org.jbpm.graph.exe.Token#204]
  | 

As read on this topic:
anonymous wrote : 
  | The stale object exceptions can be avoided by not assuming that the token cannot change through graph execution.
  | 

If I understand this correctly, this means by to introduce pessimistic locking. If so, how?
- by calling lockProcessInstance method in JbpmContext or in some other way 

Or, should I treat StaleObjectState as normal thing and according to Tom,
- http://jira.jboss.com/jira/browse/JBPM-995

anonymous wrote : 
  | When running in a cluster, jBPM synchronizes on the database. By default with optimistic locking. This means that each operation is performed in a transaction. And if at the end a collision is detected, then the transaction is rolled back and has to be handled. E.g. by a retry. So optimistic locking exceptions are usually part of the normal operation. 
  | 

implement retry logic in callback methods?

Thanks for clarifications
Milan

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