[gecode-users] Naive CCP ask in Gecode

[Guido Tack]

Mauricio Toro wrote:

> I am trying to do a naive CCP ask in Gecode and
> I am getting "Bus error".
>
> The idea is doing this process inside a thread
> ask (a = 1) do tell( b = 1)
>
> I am doing it like this:
>
>  while ( not root[i].assigned() ){ };
>    if (root[i].val() == 1)
>       rel(this, root[j], IRT_EQ, 1);
>
> Any clues why I am getting "Bus error",

Most probably because Gecode is quite simply not thread safe!  You  
cannot use the same space in two threads, concurrently performing  
operations on it (like propagation or querying of values).  Gecode was  
very consciously designed like this.  The only way multiple threads  
can safely access Gecode is if they operate on different spaces that  
have no shared data.

Cheers,
	Guido

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