Decision Optimization

Decision Optimization

Delivers prescriptive analytics capabilities and decision intelligence to improve decision-making.


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  • 1.  CPLEX Out-of-memory status

    Posted 05/21/20 06:39 PM
    Hello,

    After updating to CPLEX 12.10, I keep getting out-of-memory error when trying to solve a problem. It's weird because sometimes it runs the MIP completely and others it gives out-of-memory error. With CPLEX 12.9 the sucess rate is better, but still get out-of-memory sometimes.

    I'm running it in a Windows server 2012 OS with Intel Xeon E5-2670 @ 2.60 GHz and 48 GB RAM.

    Tried turning memory emphasis on and using node files for storage, but without success.

    Attached is a piscture from a log file before I tried memory emphasis and node file storage.

    Any advices about what can I do?

    ------------------------------
    Saulo Silva
    ------------------------------

    #DecisionOptimization


  • 2.  RE: CPLEX Out-of-memory status

    Posted 05/21/20 07:58 PM
    Tried to change the following parameters, but still getting out-of-memory error. I'm running it through python.

    optsolver.options['mip_strategy_file'] = 3;
    optsolver.options['emphasis_memory'] = 'y';
    optsolver.options['workmem'] = 12048;

    ------------------------------
    Saulo Silva
    ------------------------------



  • 3.  RE: CPLEX Out-of-memory status

    Posted 05/22/20 02:56 AM
    Edited by System Admin 01/20/23 04:43 PM
    Hi,

    I recommend https://www.ibm.com/support/pages/diagnosing-cplex-error-1001-out-memory#item4


    and in particular


    If you are taking advantage of the parallel CPLEX optimizers, reducing the number of threads in use typically also reduces memory usage. However, this may adversely impact performance, in which case one should view this as a short term solution.


    so you could try

    opt.options['threads'] = 1



    ------------------------------
    ALEX FLEISCHER
    ------------------------------

    Original Message


  • 4.  RE: CPLEX Out-of-memory status

    Posted 05/22/20 07:22 AM
    It's possible to use an intermediate number of threads, so the performance is not very impacted? The log file shows that I have up to 8 threads.

    Just tried with the three parameters above and CPLEX 12.9 and the problem was sovled, but with 12.10 I'm still getting the error.

    ------------------------------
    Saulo Silva
    ------------------------------

    Original Message


  • 5.  RE: CPLEX Out-of-memory status

    Posted 05/25/20 01:00 AM
    Could you share one of the offending problem instances? If you don't want to reduce the global thread count you could try to only reduce the auxiliary threads at the root node. To do this use auxrootthreads parameter.

    ------------------------------
    Daniel Junglas
    ------------------------------

    Original Message


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