[SCIP] Long runtimes of VRP solver

[Shen Li]

Dear SCIP mailing list

I just compiled the VRP example of the SCIP package, and I obtained the following output for eil22.vrp (part of the SCIP/VRP data files):

(…)
 time | node  | left  |LP iter|LP it/n| mem |mdpt |frac |vars |cons |cols |rows |cuts |confs|strbr|  dualbound   | primalbound  |  gap   
(…)
  428s|   300 |    15 |554079 |1689.8 | 256M|  20 |  29 |  37k| 273 |  13k| 273 |   2 |   0 | 421 | 3.687105e+02 | 3.750000e+02 |   1.71%

SCIP Status        : problem is solved [optimal solution found]
Solving Time (sec) : 476.24
Solving Nodes      : 359
Primal Bound       : +3.75000000000000e+02 (23 solutions)
Dual Bound         : +3.75000000000000e+02
Gap                : 0.00 %
SCIP Status        : problem is solved [optimal solution found]
Total Time         :     476.24
  solving          :     476.24
  presolving       :       0.00 (included in solving)
  reading          :       0.00
  copying          :       0.06 (3 #copies) (minimal 0.02, maximal 0.03, average 0.02)
(…)

I found it surprising that it took 428 seconds to solve this instance, which is typically solved within fractions of a second. Is this is similar to the behaviour you have observed? If not, any pointers to where I may have gone wrong would be greatly appreciated!

Many thanks

Shen
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