Gurobi Error for bigger Models: Failed to create model (Java)

Awaiting user input

Tobias Buchegger

May 26, 2022 19:15

• 
• 

Hello.

I have an Error when i try to run my program for bigger Models.
n<=4 ... it is working
n>4 ... it is not working

 

Error:
Exception in thread "main" gurobi.GRBException: Failed to create model
    at gurobi.GRBModel.<init>(GRBModel.java:68)
    at Chess_queenproblem.branchAndBound(Chess_queenproblem.java:82)
    at Chess_queenproblem.branchAndBound(Chess_queenproblem.java:192)
    ..... [it is recursive so i have for each new tray the same error] ...
    at Chess_queenproblem.main(Chess_queenproblem.java:53)
Warning: Failed to open log file 'LP.log'

Part of program:
public static void main(String[] arg) throws GRBException
    {     
        //Parameter values
        int n = 5;
        private static Double[][][][] threatedFields = ....;
        private static Boolean[][] fixedFields = ....;
        //Start Groubi
        env = new GRBEnv(true);
        env.set("logFile", "LP.log");
        env.set("OutputFlag", "0");
        env.start();//Start Branch and Bound
       //Start Branch and Bound
        solution  = branchAndBound(threatedFields, fixedFields,n); == Line 53
        env.dispose();

private static boolean[][] branchAndBound(Double[][][][] threatedFields, Boolean[][] fixedFields, int n) throws GRBException
    {
        GRBModel model = new GRBModel(env);
        GRBVar[][] x = new GRBVar[n][n]; == Line 83
        ... do optimization ...
        boolean[][] solutionTrue = branchAndBound(threatedFields, fixedFieldsEnlargedTrue, n); == Line 192
                        

Log:

Gurobi 9.5.1 (win64, Java) logging started Thu May 26 20:36:04 2022 >>> not working n=5 
Gurobi 9.5.1 (win64, Java) logging started Thu May 26 20:36:04 2022 >>> working n=4
        Set parameter LogFile to value "LP.log"

0

• 

  Jaromił Najman

  • Gurobi Staff

  May 30, 2022 08:27

  Did you check whether your program does run out of memory? This is often the case for recursive Java programs which require many objects of significant size, cf. StackOverflowError Vs OurOfMemoryError in Java.

  Did you try re-writing your program in a sequential way to avoid recursion?

  Best regards, 
  Jaromił

  0

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