Decision Optimization

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  • 1.  CPLEX error: nonzero return code -9

    Posted Mon December 27, 2021 04:57 AM

    Hi support,

    We've been using CPLEX to solve large scale MIP problem for few years, while recently an issue happened quite frequently.

    In the middle of solving, CPLEX often exited abnormally and it returned nonzero code -9. Find the log below.

    It seemed everything worked well at the beginning, but always ended up with the -9 error without knowing the reason. This issue has happened in several different MIP problems and it seemed very randomly.

    Please help to check this out. Thank you!

    Welcome to IBM(R) ILOG(R) CPLEX(R) Interactive Optimizer 12.10.0.0 with Simplex, Mixed Integer & Barrier Optimizers 5725-A06 5725-A29 5724-Y48 5724-Y49 5724-Y54 5724-Y55 5655-Y21 Copyright IBM Corp. 1988, 2019. All Rights Reserved. Type 'help' for a list of available commands. Type 'help' followed by a command name for more information on commands. CPLEX> Logfile 'cplex.log' closed. Logfile '/workspaces/family_design/opt/1222_opt/cplex.log' open. CPLEX> New value for time limit in seconds: 40000 CPLEX> New value for reduced memory emphasis: yes CPLEX> New value for default parallel thread count: 64 CPLEX> New value for method for linear optimization: 4 CPLEX> New value for directory for CPLEX working files: /workspaces/family_design/opt/1222_opt CPLEX> Problem '/var/tmp/pbs.1.ip-0A00040A/tmp7zp1lnx7.pyomo.lp' read. Read time = 0.48 sec. (40.37 ticks) CPLEX> Problem name : /var/tmp/pbs.1.ip-0A00040A/tmp7zp1lnx7.pyomo.lp Objective sense : Minimize Variables : 113384 [Nneg: 71, Box: 112477, Binary: 836] Objective nonzeros : 112547 Linear constraints : 496726 [Less: 496572, Equal: 154] Nonzeros : 1106388 RHS nonzeros : 224 Variables : Min LB: 0.000000 Max UB: 1.000000 Objective nonzeros : Min : 55.93226 Max : 7117.504 Linear constraints : Nonzeros : Min : 1.000000 Max : 1.000000 RHS nonzeros : Min : 1.000000 Max : 50.00000 CPLEX> Version identifier: 12.10.0.0 | 2019-11-26 | 843d4de CPXPARAM_LPMethod 4 CPXPARAM_Threads 64 CPXPARAM_Emphasis_Memory 1 CPXPARAM_TimeLimit 40000 CPXPARAM_WorkDir "/workspaces/family_design/opt/1222_opt" Tried aggregator 2 times. MIP Presolve eliminated 252186 rows and 23 columns. Aggregator did 73 substitutions. Reduced MIP has 244467 rows, 113288 columns, and 601854 nonzeros. Reduced MIP has 751 binaries, 0 generals, 0 SOSs, and 0 indicators. Presolve time = 1.17 sec. (2781.69 ticks) Probing fixed 13 vars, tightened 1 bounds. Probing time = 0.13 sec. (116.17 ticks) Tried aggregator 2 times. Detecting symmetries... MIP Presolve eliminated 1189 rows and 48 columns. Aggregator did 2 substitutions. Reduced MIP has 243276 rows, 113238 columns, and 599417 nonzeros. Reduced MIP has 737 binaries, 59 generals, 0 SOSs, and 0 indicators. Presolve time = 0.44 sec. (408.56 ticks) Probing time = 0.05 sec. (34.56 ticks) Clique table members: 857. MIP emphasis: balance optimality and feasibility. MIP search method: dynamic search. Parallel mode: deterministic, using up to 64 threads. Root relaxation solution time = 0.62 sec. (925.21 ticks) Nodes Cuts/ Node Left Objective IInf Best Integer Best Bound ItCnt Gap * 0+ 0 180446.9922 671.4276 99.63% * 0+ 0 140039.0888 671.4276 99.52% 0 0 126660.1676 337 140039.0888 126660.1676 1412 9.55% 0 0 126742.2878 337 140039.0888 Cuts: 192 2273 9.50% 0 0 126804.1437 337 140039.0888 Cuts: 215 2715 9.45% * 0+ 0 130117.2914 126804.1437 2.55% ... Elapsed time = 2869.03 sec. (402621.26 ticks, tree = 10379.35 MB, solutions = 57) Nodefile size = 8362.19 MB (4590.34 MB after compression) 31621 12638 127226.7317 197 127254.1535 127155.2500 3292816 0.08% 32093 13408 127206.3650 174 127254.1535 127156.1216 3422787 0.08% 32678 13699 127234.6676 228 127254.1535 127156.1216 3472632 0.08% 33255 13691 127244.1094 217 127254.1535 127157.1192 3472200 0.08% 33831 13904 cutoff 127254.1535 127160.2332 3509650 0.07% 34420 14344 127245.8576 116 127254.1535 127160.3870 3584079 0.07% 34997 14722 127243.1036 187 127254.1535 127160.3870 3652349 0.07% 35539 14843 127240.6279 148 127254.1535 127162.5212 3677128 0.07% ERROR: Solver (cplex) returned non-zero return code (-9) ERROR: See the solver log above for diagnostic information.






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  • 2.  RE: CPLEX error: nonzero return code -9

    Posted Sat January 08, 2022 12:38 AM

    Are you solving the model directly in CPLEX interactive optimizer or through some third-party library? If you are not solving the model directly interactive optimizer, please try to export the model and solve it directly in interactive optimizer.






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  • 3.  RE: CPLEX error: nonzero return code -9

    Posted Thu January 13, 2022 07:36 AM

    Thanks for the response.


    In fact, we called CPLEX in Pyomo (a Python based optimization platform). As shown in the log above, the Pyomo model would be transformed to file "/var/tmp/pbs.1.ip-0A00040A/tmp7zp1lnx7.pyomo.lp" and then solved by CPLEX through interactive optimizer.


    Is that what you mean about "solving the model directly in CPLEX interactive optimizer"?






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  • 4.  RE: CPLEX error: nonzero return code -9

    Posted Thu January 13, 2022 05:13 PM

    Yes and no. When you use Pyomo, the error of interactive optimizer you get is indirect. The error was intercepted by Pyomo and displayed to you. The original behavior might not be fully visible. When something doesn't work as expected, it is better to isolate the issue by removing dependencies as many as you can. Here the key point is to bypass Pyomo (by using the model exported by Pyomo) and see whether interactive optimizer actually crashes or gives some errors/warnings.






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