[SCIP] Copying SCIP with active pricers fails

[Ambros Gleixner]

Hi Alex,

Sorry for the longer wait.  You clearly identified a logical bug here.

One workaround might be:
1. deactivate your pricer in the sourcescip by SCIPdeactivatePricer()
2. copy (with enablepricing=TRUE)
3. activate your pricer again in the sourcescip
4. find pricer in the targetscip and activate it

Please let us know if that works or not.  We will look into fixing this 
cleanly in future versions.

Best,
Ambros


Am 24.07.2023 um 11:57 schrieb Alexander Helber:
> Dear SCIP community,
> 
> I am working on a branch-and-price approach for a specific problem and 
> wanted to add a simple heuristic which solves the same problem with some 
> variables fixed. I implemented the copying callbacks for my problem data 
> and pricer, but now face the problem that `SCIPcopy` throws an exception 
> due to the SCIP copy being in the wrong stage.
> 
> The SCIP copy is a freshly created instance and therefore the INIT 
> stage, as expected by `SCIPcopy` (see `scip_copy:2888` in SCIP 8.0.2). 
> But then the pricers are added and activated (`set.c:911`), which is 
> only possible in the PROBLEM stage (`scip_pricer.c:380`). I can not find 
> a use of `SCIPcopy` with pricing enabled in the codebase of the SCIP 
> Optimization Suite, so it is unclear to me if I should do something 
> different here. I would greatly appreciate your help.
> 
> All the best
> Alex
> 
> 
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