When will gurobi perform another presolving?
回答済みI have two "mathematically equivalent" models. The only difference between Model 1 and Model 2 is that Model 1 has 20w redundant constraints more than Model 2.
Here is the log for Model 2:
```
Gurobi Optimizer version 12.0.2 build v12.0.2rc0 (linux64 - "Ubuntu 22.04.4 LTS")
CPU model: Intel(R) Xeon(R) Gold 5218R CPU @ 2.10GHz, instruction set [SSE2|AVX|AVX2|AVX512]
Thread count: 20 physical cores, 40 logical processors, using up to 20 threads
Non-default parameters:
TimeLimit 86400
MIPGap 0.001
Optimize a model with 1883425 rows, 896580 columns and 9398994 nonzeros
Model fingerprint: 0xfd2c8cac
Variable types: 4718 continuous, 891862 integer (891862 binary)
Coefficient statistics:
Matrix range [1e+00, 9e+04]
Objective range [1e+00, 1e+00]
Bounds range [1e+00, 9e+04]
RHS range [1e+00, 4e+05]
Presolve removed 845913 rows and 699146 columns (presolve time = 5s)...
Presolve removed 857477 rows and 700495 columns (presolve time = 10s)...
Presolve removed 863689 rows and 701805 columns (presolve time = 15s)...
Presolve removed 878786 rows and 702296 columns (presolve time = 21s)...
Presolve removed 951365 rows and 711700 columns (presolve time = 25s)...
Presolve removed 979550 rows and 714060 columns (presolve time = 30s)...
Presolve removed 990421 rows and 715136 columns (presolve time = 35s)...
Presolve removed 1020351 rows and 715796 columns (presolve time = 40s)...
Presolve removed 1027119 rows and 717115 columns (presolve time = 45s)...
Presolve removed 1031222 rows and 717529 columns (presolve time = 50s)...
Presolve removed 1035704 rows and 718476 columns (presolve time = 55s)...
Presolve removed 1040179 rows and 719150 columns (presolve time = 60s)...
Presolve removed 1041771 rows and 719640 columns (presolve time = 65s)...
Presolve removed 1045955 rows and 720092 columns (presolve time = 70s)...
Presolve removed 1047721 rows and 720385 columns (presolve time = 75s)...
Presolve removed 1048836 rows and 720576 columns (presolve time = 80s)...
Presolve removed 1074938 rows and 733429 columns (presolve time = 85s)...
Presolve removed 1074938 rows and 733429 columns
Presolve time: 85.48s
Presolved: 808487 rows, 163151 columns, 3664881 nonzeros
Variable types: 2899 continuous, 160252 integer (160252 binary)
Performing another presolve...
Presolve removed 1672 rows and 297 columns (presolve time = 5s)...
Presolve removed 8229 rows and 350 columns (presolve time = 10s)...
Presolve removed 8432 rows and 366 columns (presolve time = 15s)...
Presolve removed 8799 rows and 436 columns (presolve time = 20s)...
Presolve removed 10383 rows and 497 columns (presolve time = 25s)...
Presolve removed 10758 rows and 566 columns (presolve time = 30s)...
Presolve removed 10842 rows and 577 columns (presolve time = 35s)...
Presolve removed 10842 rows and 577 columns (presolve time = 40s)...
Presolve removed 10842 rows and 577 columns (presolve time = 45s)...
Presolve removed 15354 rows and 1421 columns (presolve time = 50s)...
Presolve removed 16180 rows and 1471 columns (presolve time = 55s)...
Presolve removed 16180 rows and 1471 columns
Presolve time: 55.53s
Deterministic concurrent LP optimizer: primal simplex, dual simplex, and barrier
Showing barrier log only...
Root relaxation presolved: 161664 rows, 953864 columns, 3762610 nonzeros
```
Here is the log for Model 1:
```
Gurobi Optimizer version 12.0.2 build v12.0.2rc0 (linux64 - "Ubuntu 22.04.4 LTS")
CPU model: Intel(R) Xeon(R) Gold 5218R CPU @ 2.10GHz, instruction set [SSE2|AVX|AVX2|AVX512]
Thread count: 20 physical cores, 40 logical processors, using up to 20 threads
Non-default parameters:
TimeLimit 86400
MIPGap 0.001
Optimize a model with 2083993 rows, 896580 columns and 10000698 nonzeros
Model fingerprint: 0x47d7010c
Variable types: 4718 continuous, 891862 integer (891862 binary)
Coefficient statistics:
Matrix range [1e+00, 9e+04]
Objective range [1e+00, 1e+00]
Bounds range [1e+00, 9e+04]
RHS range [1e+00, 4e+05]
Presolve removed 847900 rows and 633937 columns (presolve time = 5s)...
Presolve removed 860995 rows and 636192 columns (presolve time = 10s)...
Presolve removed 868199 rows and 637619 columns (presolve time = 15s)...
Presolve removed 886159 rows and 639034 columns (presolve time = 20s)...
Presolve removed 959085 rows and 648314 columns (presolve time = 25s)...
Presolve removed 981960 rows and 649943 columns (presolve time = 30s)...
Presolve removed 999765 rows and 652552 columns (presolve time = 35s)...
Presolve removed 1004759 rows and 653780 columns (presolve time = 40s)...
Presolve removed 1031828 rows and 654561 columns (presolve time = 45s)...
Presolve removed 1042936 rows and 657096 columns (presolve time = 50s)...
Presolve removed 1047882 rows and 657641 columns (presolve time = 55s)...
Presolve removed 1056047 rows and 659473 columns (presolve time = 60s)...
Presolve removed 1060690 rows and 660308 columns (presolve time = 65s)...
Presolve removed 1065948 rows and 661609 columns (presolve time = 70s)...
Presolve removed 1070266 rows and 662580 columns (presolve time = 75s)...
Presolve removed 1072358 rows and 663216 columns (presolve time = 80s)...
Presolve removed 1073745 rows and 663518 columns (presolve time = 85s)...
Presolve removed 1075981 rows and 664292 columns (presolve time = 90s)...
Presolve removed 1077138 rows and 664582 columns (presolve time = 95s)...
Presolve removed 1105269 rows and 677561 columns (presolve time = 100s)...
Presolve removed 1105275 rows and 677568 columns (presolve time = 413s)...
Presolve removed 1105275 rows and 686380 columns (presolve time = 452s)...
Presolve removed 1131727 rows and 686546 columns (presolve time = 455s)...
Presolve removed 1136763 rows and 686560 columns (presolve time = 460s)...
Presolve removed 1137972 rows and 686580 columns (presolve time = 465s)...
Presolve removed 1138087 rows and 686618 columns
Presolve time: 467.16s
Presolved: 945906 rows, 209962 columns, 4027041 nonzeros
Variable types: 2891 continuous, 207071 integer (207071 binary)
Deterministic concurrent LP optimizer: primal simplex, dual simplex, and barrier
Showing barrier log only…
```
We have two questions:
1. When will gurobi perform another presolving? It seems very effective (In log of Model 2).
2. In log of Model 1, gurobi seems stuck at certain point:
```
Presolve removed 1105269 rows and 677561 columns (presolve time = 100s)...
Presolve removed 1105275 rows and 677568 columns (presolve time = 413s)...
```
Could you explain this situation?
Thanks
-
It might depend on the redundant constraints. I created a ticket, so that you can share the models and we could have a closer look.
0 -
Since we did not receive a model file, we're unfortunately unable to investigate this behavior further and will close this thread. Please feel free to open a new post with a reproducible example if you encounter the same issue again.
0
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