Decision Optimization

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  • 1.  callbacks and configuration for dist-mip from java client

    Posted 02/03/21 07:39 AM
    Hi

    if I set a parameter on the master like this:

    cplex.setParam( IloCplex.Param.MIP.Strategy.File, 3);
    // Load the virtual machine configuration.
    // This will force solve() to use distributed parallel MIP.
    cplex.readVMConfig(vmconfig);

    will CPLEX apply the configuration to every worker ?

    Also , what callbacks are available for dist-mip, and will the chosen callbacks only apply to the master, or to all  the workers as well ?
    This discussion was started on the old forum which is not available now.

    Thanks a lot.

    ------------------------------
    srinivas tamvada
    ------------------------------

    #DecisionOptimization


  • 2.  RE: callbacks and configuration for dist-mip from java client

    Posted 02/03/21 09:00 AM
    Hi

    In https://www.ibm.com/support/knowledgecenter/SSSA5P_20.1.0/ilog.odms.cplex.help/CPLEX/UsrMan/topics/parallel_optim/distribMIP/01_distributed_mip_title_synopsis.html

    You may read

    <main role="main">

    By default, workers inherit the parameter settings of the master, but you can apply different parameter settings for different workers in the VMC file.

    </main>

    you have an example in CPLEX_Studio201\cplex\examples\src\distmipjava : DistMIPEx2

    regards

    ------------------------------
    [Alex] [Fleischer]
    [EMEA CPLEX Optimization Technical Sales]
    [IBM]
    ------------------------------



  • 3.  RE: callbacks and configuration for dist-mip from java client

    Posted 02/03/21 01:10 PM
    thank you for the note

    please comment on the other part of the question : are callbacks  available for dist-mip, and will the chosen callbacks only apply to the master, or to all the workers as well ?  In fact in my opinion callbacks have not much to do on the master, because most of the action is on the workers.

    ------------------------------
    srinivas tamvada
    ------------------------------

    Original Message


  • 4.  RE: callbacks and configuration for dist-mip from java client

    Posted 02/03/21 01:23 PM
    Hi,

    in the same documentation

    No legacy control or query callbacks 

Distributed parallel MIP does not support legacy control callbacks. Distributed parallel MIP does not support legacy query callbacks. 

For definitions of legacy informational, query, and control callbacks, see the topic Using legacy optimization callbacks in the CPLEX User's Manual. 


Special considerations about legacy informational callbacks

You can use legacy informational callbacks with distributed parallel MIP in certain situations. An informational callback pertains to the master (not the workers). Furthermore, during rampup, there is no uniquely defined tree. Consequently, callback information that depends on specifics of a branch and bound tree does not exist then. 
​


    ------------------------------
    [Alex] [Fleischer]
    [EMEA CPLEX Optimization Technical Sales]
    [IBM]
    ------------------------------

    Original Message


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