[kepler-dev] PN + NondeterministicMerge bug/question

Norbert Podhorszki pnorbert at cs.ucdavis.edu
Sat Jul 22 18:54:39 PDT 2006


I have created a small workflow to demonstrate the Switch actor. A Ramp 
produces numbers 1..10, an Expression produces 0..2 (input mod 3), and the 
Switch has three channels, each with just one Expression to produce a 
String. Finally, the three branches are brough together with 
NondeterministicMerge and the strings are displayed.

So there I expect 10 strings as output, which is mostly the case if I run 
it. However, sometimes - quite frequently - less strings are displayed 
(tokens somewhere are lost) when the workflow stops.

The workflow works nicely if I do one of the followings:
  - replace NondeterministicActor for Select
  - put a Sleep with 1ms to slow down the execution

So it seems to me that PN senses termination condition wrongly in the 
original case. Or what else?

I attach the workflow, already with the Sleep, so it works as expected.
If you delete the Sleep actor (or even just set to 0) and run it a couple 
of times, you will see shorter outputs occasionally.

I would like to understand what is happening and why (except if it is a 
Thanks in advance for explanation.

      Norbert Podhorszki
      University of California, Davis
      Department of Computer Science
      1 Shields Ave, 2236 Kemper Hall
      Davis, CA 95616
      (530) 754-8188
      pnorbert at cs.ucdavis.edu
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