[Cbc] Parallell CBC

Wed Jul 13 02:54:51 EDT 2016

Dear CBC,

I am using CBC 2.9.4 for MILP problem, but is not able to run in parallel.  Using the option "-threads <some number>" makes CBC hang after a few seconds.
Is there a new Win64 cbc.exe that properly handles the "-threads" option?  (And possibly with improved MILP performance?)

CBC stops after the following print:
C:\Users\bjorn_000>C:\Users\bjorn_000\AppData\Roaming\Microsoft\AddIns\Solvers\win64\cbc.exe -threads 2 -directory "C:\Dropbox\kh\Optimize\ModelsAndSolutions" -import "C:\Dropbox\kh\Optimize\ModelsAndSolutions\ModelForGurobi.lp" -seconds 20 -maxIterations 50000 -ratioGap 0 -solve -solution "C:\Dropbox\kh\Optimize\ModelsAndSolutions\Solution.txt"
Welcome to the CBC MILP Solver
Version: 2.9.4
Build Date: May 18 2015

command line - C:\Users\bjorn_000\AppData\Roaming\Microsoft\AddIns\Solvers\win64\cbc.exe -threads 2 -directory C:\Dropbox\kh\Optimize\ModelsAndSolutions -import C:\Dropbox\kh\Optimize\ModelsAndSolutions\ModelForGurobi.lp -seconds 20 -maxIterations 50000 -ratioGap 0 -solve -solution C:\Dropbox\kh\Optimize\ModelsAndSolutions\Solution.txt (default strategy 1)
threads was changed from 0 to 2
seconds was changed from 1e+100 to 20
maxIterations was changed from 2147483647 to 50000
ratioGap was changed from 0 to 0
Continuous objective value is 178.167 - 0.09 seconds
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 5 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0003I 0 fixed, 0 tightened bounds, 1 strengthened rows, 0 substitutions
Cgl0004I processed model has 2400 rows, 2976 columns (2973 integer (1497 of which binary)) and 43145 elements
Cbc0038I Initial state - 16 integers unsatisfied sum - 3.95151
Cbc0038I Pass   1: suminf.    1.27858 (7) obj. 786.122 iterations 1458
Cbc0038I Pass   2: suminf.    0.82530 (3) obj. 1498.29 iterations 288
Cbc0038I Solution found of 1498.29
Cbc0038I Branch and bound needed to clear up 3 general integers
Cbc0038I Full problem 2400 rows 2976 columns, reduced to 19 rows 17 columns
Cbc0038I Cleaned solution of 1092.61
Cbc0038I Before mini branch and bound, 2948 integers at bound fixed and 1 continuous of which 1 were internal integer and 0 internal continuous
Cbc0038I Full problem 2400 rows 2976 columns, reduced to 32 rows 24 columns
Cbc0038I Mini branch and bound did not improve solution (1.10 seconds)
Cbc0038I Freeing continuous variables gives a solution of 1092.61
Cbc0038I Round again with cutoff of 1001.22
Cbc0038I Reduced cost fixing fixed 31 variables on major pass 2
Cbc0038I Pass   3: suminf.    1.27858 (7) obj. 786.122 iterations 0
Cbc0038I Pass   4: suminf.    1.24256 (7) obj. 1001.22 iterations 961
Cbc0038I Pass   5: suminf.    0.73804 (7) obj. 1001.22 iterations 5
Cbc0038I Pass   6: suminf.    1.20089 (5) obj. 1001.22 iterations 1597
Cbc0038I Pass   7: suminf.    1.24057 (5) obj. 1001.22 iterations 622
Cbc0038I Solution found of 1001.22
Cbc0038I Branch and bound needed to clear up 5 general integers
Cbc0038I Mini branch and bound could not fix general integers
Cbc0038I No solution found this major pass
Cbc0038I Before mini branch and bound, 2941 integers at bound fixed and 1 continuous
Cbc0038I Full problem 2400 rows 2976 columns, reduced to 42 rows 32 columns
Cbc0038I Mini branch and bound did not improve solution (1.69 seconds)
Cbc0038I After 1.69 seconds - Feasibility pump exiting with objective of 1092.61 - took 0.94 seconds
Cbc0012I Integer solution of 1092.6135 found by feasibility pump after 0 iterations and 0 nodes (1.69 seconds)
Cbc0038I Full problem 2400 rows 2976 columns, reduced to 32 rows 24 columns
Cbc0012I Integer solution of 719.2773 found by RINS after 0 iterations and 0 nodes (1.84 seconds)
Cbc0031I 11 added rows had average density of 528.81818
Cbc0013I At root node, 11 cuts changed objective from 178.71006 to 179.04079 in 10 passes
Cbc0014I Cut generator 0 (Probing) - 0 row cuts average 0.0 elements, 1 column cuts (1 active)  in 0.598 seconds - new frequency is 1
Cbc0014I Cut generator 1 (Gomory) - 12 row cuts average 1499.0 elements, 0 column cuts (0 active)  in 0.095 seconds - new frequency is 1
Cbc0014I Cut generator 2 (Knapsack) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.054 seconds - new frequency is -100
Cbc0014I Cut generator 3 (Clique) - 0 row cuts average 0.0 elements, 0 column cuts (0 active)  in 0.002 seconds - new frequency is -100
Cbc0014I Cut generator 4 (MixedIntegerRounding2) - 14 row cuts average 652.2 elements, 0 column cuts (0 active)  in 0.166 seconds - new frequency is 1
Cbc0014I Cut generator 5 (FlowCover) - 8 row cuts average 4.5 elements, 0 column cuts (0 active)  in 0.023 seconds - new frequency is 1
Cbc0014I Cut generator 6 (TwoMirCuts) - 2 row cuts average 6.0 elements, 0 column cuts (0 active)  in 0.058 seconds - new frequency is -100
Cbc0010I After 0 nodes, 1 on tree, 719.2773 best solution, best possible 179.04079 (3.24 seconds)
Cbc0012I Integer solution of 266.2883 found by DiveCoefficient after 104 iterations and 1 nodes (3.38 seconds)
Cbc0012I Integer solution of 266.2883 found by heuristic after 98 iterations and 0 nodes (3.56 seconds)

Best regards,

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