ortools SCIP stuck in presolve

Question

I'm using ortools to solve a Mixed-integer-problem, using SCIP as the solver.

And the solver.EnableOutput() is preformed, and the following output is displayed on my screen↓

(round 236, fast)       878 del vars, 1832 del conss, 0 add conss, 1235 chg bounds, 138 chg sides, 238 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 237, fast)       878 del vars, 1832 del conss, 0 add conss, 1235 chg bounds, 139 chg sides, 238 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 238, fast)       879 del vars, 1833 del conss, 0 add conss, 1235 chg bounds, 139 chg sides, 238 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 239, exhaustive) 879 del vars, 1833 del conss, 0 add conss, 1235 chg bounds, 139 chg sides, 241 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 240, fast)       879 del vars, 1834 del conss, 0 add conss, 1236 chg bounds, 139 chg sides, 241 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 241, fast)       881 del vars, 1835 del conss, 0 add conss, 1236 chg bounds, 139 chg sides, 241 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
(round 242, fast)       882 del vars, 1837 del conss, 0 add conss, 1236 chg bounds, 139 chg sides, 241 chg coeffs, 0 upgd conss, 0 impls, 0 clqs
   Deactivated symmetry handling methods, since SCIP was built without symmetry detector (SYM=none).
presolving (243 rounds: 243 fast, 53 medium, 53 exhaustive):
 883 deleted vars, 1837 deleted constraints, 0 added constraints, 1236 tightened bounds, 0 added holes, 139 changed sides, 241 changed coefficients
 0 implications, 0 cliques

And then python get stuck, no further print or any other display. Normally, the following output would be shown after * implications, * cliques

presolved problem has 115 variables (4 bin, 0 int, 0 impl, 111 cont) and 114 constraints
      2 constraints of type <varbound>
    112 constraints of type <linear>
Presolving Time: 0.00

 time | node  | left  |LP iter|LP it/n|mem/heur|mdpt |vars |cons |rows |cuts |sepa|confs|strbr|  dualbound   | primalbound  |  gap   | compl. 
p 0.0s|     1 |     0 |     5 |     - |   locks|   0 | 115 | 114 | 114 |   0 |  0 |   0 |   0 |-3.686091e+03 |-1.600361e+04 | 334.16%| unknown
* 0.0s|     1 |     0 |     6 |     - |    LP  |   0 | 115 | 114 | 114 |   0 |  0 |   0 |   0 |-8.756871e+03 |-8.756871e+03 |   0.00%| unknown
  0.0s|     1 |     0 |     6 |     - |  5577k |   0 | 115 | 114 | 114 |   0 |  0 |   0 |   0 |-8.756871e+03 |-8.756871e+03 |   0.00%| unknown after

So, is the problem due to the ortools solver? Or is just the problem of the input data reallyyyyyyy costs tons of time?

Laurent Perron · Accepted Answer · 2024-02-29 05:41:39Z

0

Save the model as an mps file, download the official Scip solver. Run the Scip binary on your mps file.

If the behavior is different, we will look at it, otherwise it is a Scip bug.

answered Feb 29, 2024 at 5:41

Laurent Perron

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4 Comments

Ben Yan Over a year ago

I saved the model as an mps file (ortools==9.8.3296), and downloaded the SCIP solver(SCIPOptSuite-8.1.0-win64-VS15.exe) via scipopt.org/index.php#download. Ran SCIP exe program and used console to read the mps file, and the same problem is solved.

Laurent Perron Over a year ago

can you send me the mps file ?

Laurent Perron Over a year ago

And note that or-tools 9.8 was built with scip 8.0.4

Ben Yan Over a year ago

how can I send the file to you? via email? i couldn't find your email address on your profile page

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