[Scip] consistent "double free" segfault with fscip

[Yuji Shinano]

Hi George,

I see, thank you very much for the good instance to debug.
Anyway, I have to know the bug and I am pleased to fix it.
FiberSCIP has a deterministic mode for debugging. I hope your instance
get the bug with the deterministic mode.
If I need your help, I will send you e-mail personally.
By the way, I think this top is not good for this mailing list,
this should be better to put bug-report.

I would like to recommend FiberSCIP and ParaSCIP usres
as follows in this opportunity:

1. I strongly recommend to use SCIP version 3.0.2 bug fix version released in this week.

Resetting of user interrupt flag was missing. This is a very small bug for SCIP users,
but it is a serious bug for FiberSCIP and ParaSCIP users. Current FiberSCIP and ParaSCIP
can interrupt a branch-and-bound node processing when the other solvers found a good feasible 
solution. Therefore, if a sub-MIP, which leads to an optimal solution,
is assigned to such an interrupted solver, it may lose the optimal solution.

2 Please try to use SCIP first

FiberSCIP is not alway better even if it uses many cores.
You can see it in the following FiberSCIP paper.
http://opus4.kobv.de/opus4-zib/frontdoor/index/index/docId/4259

Best,
Yuji


(13/10/19 1:21), George Nychis wrote:
> Sure, sorry Yuji.
>
> On a 6 core machine with 16GB of memory, it often takes about 6 hours to segfault.  Rarely does it
> segfault earlier than that.  If you give me pointers on how to debug it, I could also try to build
> with some debug flags, etc.
>
> I will re-run it and try to capture the output.  Previously, I was not saving this output.
>
> - George
>
>
> On Fri, Oct 18, 2013 at 4:02 PM, Yuji Shinano <shinano at zib.de <mailto:shinano at zib.de>> wrote:
>
>     So, please send me your output until it causes the segmentation fault.
>     How long did it take time to get it.
>
>     I assumed that you compiled with opt mode. Then, I compiled with
>        - Soplex: make PARASCIP=true
>        - SCIP: make PARASCIP=true
>        - UG: make
>     Currently, it is running more than 12640 sec. without the segmentation fault.
>     I need more information from you to debug it.
>
>     Best,
>     Yuji
>
>
>     (13/10/18 22:40), George Nychis wrote:
>
>         I definitely built with PARASCIP=true, and I've been using fscip for a while now with some
>         different
>         programs without an issue.  This one in particular has been segfaulting for me, though.  I
>         believe
>         that I did a standard make and built UG, SCIP, and Soplex will all of the options.
>
>         Thanks for the help!
>
>         - George
>
>
>         On Fri, Oct 18, 2013 at 12:51 PM, Yuji Shinano <shinano at zib.de <mailto:shinano at zib.de>
>         <mailto:shinano at zib.de <mailto:shinano at zib.de>>> wrote:
>
>              Hi George,
>
>
>                  I've tried this on 5 different machines now, and my MIP keeps crashing with a
>         segfault on a
>                  double
>                  free using fscip:
>
>                  *** glibc detected *** fscip: double free or corruption (!prev): 0x00007f84b57b2ae0 ***
>
>
>                  I've attached the MIP, you can run it on "obj_jainFairness.zpl"
>
>
>              Did you use Soplex and SCIP compiled with "PARASCIP=true" option?
>              Could you tell me how to build the binaries of Soplex, SCIP, UG (all options)?
>
>              Best,
>              Yuji
>
>
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