[Jolie-devel] java.lang.NullPointerException on WhileProcess-NDChoiceProcess

[Matthias D. W. <mwa...@ya...>]

Hi Fabrizio & devs,

during development of my current Jolie-based project which is some kind
of Formula 1 simulator I stumbled across the following issue:

> Exception in thread "tinyClient.ol-JolieThread-2" java.lang.NullPointerException
>         at jolie.process.NDChoiceProcess.run(NDChoiceProcess.java:95)
>         at jolie.process.WhileProcess.run(WhileProcess.java:55)
>         at jolie.process.SequentialProcess.run(SequentialProcess.java:59)
>         at jolie.process.DefinitionProcess.run(DefinitionProcess.java:46)
>         at jolie.SessionThread.run(SessionThread.java:461)

This exception occurs randomly when I run my client software (with input
and output ports) - currently still very basic (see attachment). The
real simulation happens on the server side and sends events in a push
manner ("genericEvent", "simFinished").

If I change the client to look like this the problem does no longer
appear but I have no way to shut it down remotely.

> execution { sequential }
>
> main
> {
>     [ genericEvent(event) ] {
>       println@Console(event)()
>     }
>     [ simFinished() ] {
>       nullProcess
>     }
> }

But according to the example under
http://www.jolie-lang.org/?top_menu=documentation&sideMenuAction=basics/sessions
the "while" loop approach should work.
To me the exception looks very close to some sort of race condition.

Cheers,
Matthias