[Scip] Changing time limit during solving make SCIP freeze

[Timo Berthold]

Hi Aurélien,

Could you please distinguish in your description between the original
and the sub-SCIP instance.

What I understood:
You are using the original SCIP instance for Branch-and-price, have
implemented a pricer, which solves a sub-SCIP instance (as a plain MIP,
I assume).
When a solution is found in the sub-SCIP, you want to stop this sub-SCIP
and continue solving the original? How did you do this? The only ways I
see to change the time limit of the sub-SCIP during its solving is by an
event handler.

What might have happened:
May it be that you set the timelimit in the original and not in the
sub-SCIP?

What you might do:
Set a bestsol limit of 1 for the sub-SCIP, to stop after the first
solution. I would not use time limits within the pricing codes since
this destroys determinism.

Best
Timo

Am 03.05.2013 11:41, schrieb Aurélien Questel:
> A small precision : when the time limit is reached, the solving
> process may stop and display
> the different statistics (#nodes, best sol value, etc...) 
> but then my program freezes and the following procedures of my pricer
> aren't reached.
> So I know for sure that the issue appends between the stop instruction
> and the termination of a scip instance
>
> Le 3 mai 2013 à 11:11, Aurélien Questel a écrit :
>
>> Hi all,
>> I've developed a BCP using another scip instance (solving a BC) to
>> solve the pricing problem.
>> In order to accelerate the global solving time I've tried to set a
>> (short) time limit when the first solution
>> is found during the pricing procedure. In fact, I don't need to solve
>> this problem to optimality 
>> if I have already found a valid column.
>> However I have a strange behavior, if I do so the skip instance
>> freeze when the time limit is reached.
>> I use the following instruction :     SCIP_CALL(
>> SCIPsetRealParam(scip, "limits/time", 30) );
>>
>> Does anyone have an idea ? Do I do something in the wrong way ?
>>
>> Best regards
>>
>> Aurélien
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>
>
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