[SCIP] Scip stops reporting

[Marc Pfetsch]

Hi Marco,

this behavior is of course not normal. Please tell us if you find the 
reason and report a bug through the SCIP web page.

Best

Marc


On 11/07/2021 13:16, Marco Correia wrote:
> Hi,
> 
> I'm running a problem where at some point SCIP seems to hang, or at 
> least, it stops logging. This is the output I get from it until that 
> happens:
> 
> feasible solution found by trivial heuristic after 0.0 seconds, 
> objective value 0.000000e+00
> presolving:
> (round 1, fast)       6 del vars, 9 del conss, 0 add conss, 96 chg 
> bounds, 0 chg sides, 0 chg coeffs, 0 upgd conss, 86 impls, 148 clqs
> (round 2, exhaustive) 6 del vars, 92 del conss, 0 add conss, 96 chg 
> bounds, 83 chg sides, 1 chg coeffs, 0 upgd conss, 86 impls, 148 clqs
> (round 3, exhaustive) 6 del vars, 92 del conss, 0 add conss, 96 chg 
> bounds, 83 chg sides, 1 chg coeffs, 539 upgd conss, 86 impls, 148 clqs
>    (0.0s) probing cycle finished: starting next cycle
> (round 4, exhaustive) 6 del vars, 92 del conss, 0 add conss, 177 chg 
> bounds, 83 chg sides, 1 chg coeffs, 539 upgd conss, 1028 impls, 247 clqs
> (round 5, fast)       6 del vars, 92 del conss, 0 add conss, 177 chg 
> bounds, 83 chg sides, 27 chg coeffs, 539 upgd conss, 1028 impls, 247 clqs
>    (0.0s) probing: 108/148 (73.0%) - 0 fixings, 0 aggregations, 975 
> implications, 82 bound changes
>    (0.0s) probing aborted: 50/50 successive totally useless probings
>    (0.0s) symmetry computation started: requiring (bin +, int -, cont 
> +), (fixed: bin -, int +, cont -)
>    (0.0s) no symmetry present
> presolving (6 rounds: 6 fast, 4 medium, 4 exhaustive):
> 6 deleted vars, 92 deleted constraints, 0 added constraints, 178 
> tightened bounds, 0 added holes, 83 changed sides, 27 changed coefficients
> 1068 implications, 247 cliques
> presolved problem has 421 variables (148 bin, 0 int, 0 impl, 273 cont) 
> and 837 constraints
>     193 constraints of type <varbound>
>     148 constraints of type <setppc>
>     298 constraints of type <linear>
>     198 constraints of type <logicor>
> Presolving Time: 0.02
> transformed 1/1 original solutions to the transformed problem space
> 
> time | node  | left  |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows 
> |cuts |sepa|confs|strbr|  dualbound   | primalbound  |  gap   | compl.
>   0.0s|     1 |     0 |   398 |     - |  6511k |   0 | 421 | 851 | 836 | 
>    0 |  0 |  13 |   0 | 7.631347e-02 | 0.000000e+00 |    Inf | unknown
>   0.0s|     1 |     0 |   398 |     - |  6521k |   0 | 421 | 851 | 836 | 
>    0 |  0 |  13 |   0 | 7.631347e-02 | 0.000000e+00 |    Inf | unknown
>   0.0s|     1 |     0 |   399 |     - |  6637k |   0 | 421 | 851 | 837 | 
>    1 |  1 |  13 |   0 | 7.466223e-02 | 0.000000e+00 |    Inf | unknown
>   0.0s|     1 |     0 |   414 |     - |  6782k |   0 | 421 | 851 | 838 | 
>    2 |  2 |  13 |   0 | 7.388510e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   424 |     - |  6936k |   0 | 421 | 851 | 842 | 
>    6 |  3 |  13 |   0 | 6.982341e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   433 |     - |  7114k |   0 | 421 | 851 | 845 | 
>    9 |  4 |  13 |   0 | 6.814827e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   435 |     - |  7273k |   0 | 421 | 851 | 846 | 
>   10 |  5 |  13 |   0 | 6.814318e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   442 |     - |  7418k |   0 | 421 | 851 | 847 | 
>   11 |  6 |  13 |   0 | 6.780902e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   449 |     - |  7686k |   0 | 421 | 851 | 851 | 
>   15 |  7 |  13 |   0 | 6.745065e-02 | 0.000000e+00 |    Inf | unknown
>   0.1s|     1 |     0 |   477 |     - |  7902k |   0 | 421 | 851 | 853 | 
>   17 |  8 |  13 |   0 | 6.700544e-02 | 0.000000e+00 |    Inf | unknown
>   0.2s|     1 |     0 |   485 |     - |  8009k |   0 | 421 | 852 | 855 | 
>   19 |  9 |  14 |   0 | 6.606474e-02 | 0.000000e+00 |    Inf | unknown
>   0.2s|     1 |     0 |   501 |     - |  8476k |   0 | 421 | 852 | 857 | 
>   21 | 10 |  14 |   0 | 6.543249e-02 | 0.000000e+00 |    Inf | unknown
>   0.2s|     1 |     0 |   561 |     - |  8569k |   0 | 421 | 852 | 859 | 
>   23 | 11 |  14 |   0 | 6.433780e-02 | 0.000000e+00 |    Inf | unknown
>   0.2s|     1 |     0 |   584 |     - |  8751k |   0 | 421 | 853 | 860 | 
>   24 | 12 |  15 |   0 | 6.388945e-02 | 0.000000e+00 |    Inf | unknown
>   0.2s|     1 |     0 |   585 |     - |  8845k |   0 | 421 | 854 | 861 | 
>   25 | 13 |  16 |   0 | 6.388368e-02 | 0.000000e+00 |    Inf | unknown
> time | node  | left  |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows 
> |cuts |sepa|confs|strbr|  dualbound   | primalbound  |  gap   | compl.
>   0.2s|     1 |     0 |   600 |     - |  9406k |   0 | 421 | 854 | 862 | 
>   26 | 14 |  16 |   0 | 6.351136e-02 | 0.000000e+00 |    Inf | unknown
>   0.3s|     1 |     0 |   605 |     - |  9499k |   0 | 421 | 854 | 862 | 
>   27 | 15 |  16 |   0 | 6.347853e-02 | 0.000000e+00 |    Inf | unknown
>   0.3s|     1 |     0 |   611 |     - |  9499k |   0 | 421 | 854 | 865 | 
>   30 | 16 |  16 |   0 | 6.329991e-02 | 0.000000e+00 |    Inf | unknown
>   0.4s|     1 |     2 |  1077 |     - |  9614k |   0 | 421 | 854 | 865 | 
>   30 | 18 |  16 |  26 | 6.258119e-02 | 0.000000e+00 |    Inf | unknown
> 
> I've run it with a debugger, but given it is compiled without debugging 
> symbols, I can only see that it is somewhere inside SCIPsolve.
> 
> I can dig deeper, but would first like to ask if this behaviour could be 
> normal.
> 
> Thanks
> Marco
> 
> 
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