Re: [Swarm-Support] crash at odd timestep

[Paul Johnson]

Corinne Coen wrote:
> Dear Swarm folk
>
>  
>
> I am an unsophisticated user of swarm.  I have a model I built several
> years ago (it uses swarm-2.2).  Although I recall that it worked fine
> when I built it, now, when I run it in BatchSwarm mode, it crashes at
> timestep=55.  When stopT is equal to any number from 1 through 55, it
> stops at the indicated timestep.  When stopT is set at 56 or above it
> crashes after timestep 55.  In contrast, in GUI it also crashes but at
> timestep 166.  Again with stopT set anywhere from 1-165, it stops at the
> desired step.  With stopT=166 or higher, it crashes.  I get the
> following error message:
>
>  
>
> *** event raised for error: OffsetOutOfRange
>
> *** function: indexAtOffset(), file:
> /home/pauljohn/LinuxDownloads/redhat/BUILD/swarm-2.2/src/collections/Col
> lection.m, line: 119
>
> *** execution terminating due to error
>
> /home/pauljohn/LinuxDownloads/redhat/BUILD/swarm-2.2/src/defobj/Symbol.m
> :187 -[Error(c) _raiseEvent:] Aborted
>
>  
>
> Can you help me figure out the cause of the crashes?

Now Swarm will stop when a message is sent to nil.

Look at your code for how you do iterations on list.  Try to see how an 
object might have been put equal to nil while it is still in the list.

If you are iterating with a for loop or a while loop, it is easy to 
correct these if you do

if (anObject != nil)

before telling anObject to do something.

Know what I mean?

Paul Box is right that gdb might lead to the line in your code where the 
crash is triggered, but it will not really help you figure out which 
element is nil unless you do some fancy footwork.

WHen you figure out which list is causing the trouble, then you should 
write some diagnostic code into the model.  I recall using a builtin 
function in swarm for this.  Am traveling now and can't look up in 
Reference Guide.  is it xprint or xfprintid for lists?

PJ


> Best,
>
> Corinne


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Paul E. Johnson                       email: address@hidden
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