[jboss-user] [jBPM] - Re: jBPM5 - Can't Scale, Won't Scale

[M Arnold]

M Arnold [https://community.jboss.org/people/m_arnold123] created the discussion

"Re: jBPM5 - Can't Scale, Won't Scale"

To view the discussion, visit: https://community.jboss.org/message/801971#801971

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Kris,

Thanks very much for your informative reply.  In fact we found a way to make jBPM5 scale - but it was a lot of work.  We wrote our own persistent timer implementation and execute each process instance in its own seesion.  I will write up the details in another thread soon in case it helps someone.

> 1a. it's not scalable to use a single session to execute all processes, or you would suffer contention on the session info
> 
> 
> *If you only have one session, there would be no contention as the ksession would solve this*
> 
I did not know this and this is could be the root of my misunderstanding.  But I can't understand how the ksession could solve this.  If process instance A executes in transaction Ta and process instance B executes in transaction Tb, and both transactions change the session info - which is simply a JPA entity - how do the two process instance executions NOT serialise?

> *Note that for 6.0, we will be providing a lot more advanced session management out-of-the-box. * 
This sounds good, because session handling with 5.x is very difficult to get right for jBPM users.  It's difficult enough to just detect when a session can be safely disposed. I'm not sure how other users are doing it. Unless you're not using timers, not using persistence, and happy to restart your application periodically then it's encumbant on jBPM user to write a lot of tricky session management code.  

In fact, I can see how these sessions might be useful for Drools users, but from the point-of-view of a jBPM user - who just wants to execute processes - it's hard to see what the concept of sessions gives you?  If you just want to execute business processes, why should you care about "sessions"?

Thanks again.
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