[Cbc] Options to prevent CBC from "stalling" in presolve / root node processing

[Watson, Jean-paul]

Hi all,

I have a medium-scale MIP that is behaving badly when I try to solve it with CBC. In particular, it takes around 5+ minutes just to get to the point where the feasibility pump kicks in (which turns out to quickly find an optimal solution). This is in contrast to GLPK, SCIP, CPLEX, Gurobi, etc., which get to this point in a few seconds at worst. The output trace is below.

The vast majority of the time is spent doing substitutions / variable fixing. Is there an option to either turn such processing off, or reduce the number of passes? I tried turning off all cuts and presolve, and didn't see any other options that were obvious (at least to me).

Thanks!

Jean-Paul

---

command line - cbc foo.lp (default strategy 1)
Coin0009I  CoinLpIO::readLp(): Maximization problem reformulated as minimization
Continuous objective value is -53.7 - 0.66 seconds
Cgl0002I 542 variables fixed
Cgl0003I 188 fixed, 0 tightened bounds, 0 strengthened rows, 58122 substitutions
Cgl0003I 99 fixed, 0 tightened bounds, 0 strengthened rows, 42070 substitutions
Cgl0003I 69 fixed, 0 tightened bounds, 0 strengthened rows, 41920 substitutions
Cgl0003I 72 fixed, 0 tightened bounds, 0 strengthened rows, 41792 substitutions
Cgl0003I 51 fixed, 0 tightened bounds, 0 strengthened rows, 41672 substitutions
Cgl0003I 75 fixed, 0 tightened bounds, 0 strengthened rows, 41528 substitutions
Cgl0003I 66 fixed, 0 tightened bounds, 0 strengthened rows, 41406 substitutions
Cgl0003I 72 fixed, 0 tightened bounds, 0 strengthened rows, 41258 substitutions
Cgl0003I 63 fixed, 0 tightened bounds, 0 strengthened rows, 41118 substitutions
Cgl0003I 2320 fixed, 0 tightened bounds, 0 strengthened rows, 0 substitutions
Cgl0003I 2324 fixed, 0 tightened bounds, 0 strengthened rows, 2 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 0 strengthened rows, 1 substitutions
Cgl0004I processed model has 777 rows, 6796 columns (6795 integer) and 17610 elements
Cbc0038I Pass   1: suminf.    0.00000 (0) obj. -25 iterations 938
Cbc0038I Solution found of -25
Cbc0038I Before mini branch and bound, 6715 integers at bound fixed and 0 continuous
Cbc0038I Full problem 777 rows 6796 columns, reduced to 20 rows 20 columns
Cbc0038I Mini branch and bound improved solution from -25 to -27 (840.93 seconds)
Cbc0038I Round again with cutoff of -27.065
Cbc0038I Pass   2: suminf.    1.30018 (16) obj. -27.065 iterations 475
Cbc0038I Pass   3: suminf.    1.04014 (16) obj. -27.065 iterations 89
Cbc0038I Pass   4: suminf.    1.04014 (14) obj. -27.065 iterations 612
Cbc0038I Pass   5: suminf.    0.91013 (14) obj. -27.065 iterations 72
Cbc0038I Pass   6: suminf.    0.91013 (12) obj. -27.065 iterations 536
Cbc0038I Pass   7: suminf.    0.78011 (12) obj. -27.065 iterations 55
Cbc0038I Pass   8: suminf.    1.04014 (12) obj. -27.065 iterations 528
Cbc0038I Pass   9: suminf.    0.78011 (12) obj. -27.065 iterations 239
Cbc0038I Pass  10: suminf.    0.91013 (12) obj. -27.065 iterations 529
Cbc0038I Pass  11: suminf.    0.78011 (11) obj. -27.065 iterations 85
Cbc0038I Pass  12: suminf.    1.30018 (12) obj. -27.065 iterations 437
Cbc0038I Pass  13: suminf.    0.78011 (12) obj. -27.065 iterations 270
Cbc0038I Pass  14: suminf.    1.43020 (12) obj. -27.065 iterations 471
Cbc0038I Pass  15: suminf.    0.78011 (11) obj. -27.065 iterations 136
Cbc0038I Pass  16: suminf.    1.17016 (12) obj. -27.065 iterations 488
Cbc0038I Pass  17: suminf.    0.78011 (11) obj. -27.065 iterations 130
Cbc0038I Pass  18: suminf.    1.04014 (11) obj. -27.065 iterations 468
Cbc0038I Pass  19: suminf.    0.78011 (12) obj. -27.065 iterations 144
Cbc0038I Pass  20: suminf.    1.56022 (12) obj. -27.065 iterations 475
Cbc0038I Pass  21: suminf.    0.78011 (11) obj. -27.065 iterations 150
Cbc0038I Pass  22: suminf.    1.04014 (11) obj. -27.065 iterations 462
Cbc0038I Pass  23: suminf.    0.78011 (12) obj. -27.065 iterations 145
Cbc0038I Pass  24: suminf.    3.90054 (26) obj. -27.065 iterations 458
Cbc0038I Pass  25: suminf.    1.62522 (21) obj. -27.065 iterations 375
Cbc0038I Pass  26: suminf.    3.17016 (21) obj. -27.065 iterations 484
Cbc0038I Pass  27: suminf.    1.43020 (20) obj. -27.065 iterations 439
Cbc0038I Pass  28: suminf.    3.49521 (19) obj. -27.065 iterations 517
Cbc0038I Pass  29: suminf.    1.36519 (18) obj. -27.065 iterations 411
Cbc0038I Pass  30: suminf.    2.84512 (18) obj. -27.065 iterations 440
Cbc0038I Pass  31: suminf.    1.36519 (16) obj. -27.065 iterations 504
Cbc0038I No solution found this major pass
Cbc0038I Before mini branch and bound, 6498 integers at bound fixed and 0 continuous
Cbc0038I Full problem 777 rows 6796 columns, reduced to 55 rows 170 columns
Cbc0038I Mini branch and bound did not improve solution (841.72 seconds)
Cbc0038I After 841.72 seconds - Feasibility pump exiting with objective of -27 - took 0.90 seconds

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