If solver hits time limit, is a solution output?

Answered

Sam Ganzfried

• February 04, 2020 14:32

I am just wondering if the time limit parameter is set and the algorithm hits the time limit, does it still output a solution (whatever the best/current iteration of the algorithm has produced)? Obviously it wouldn't be an optimal solution, but I am just wondering if an approximate solution is still output in this case.

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• 

  Yuriy Zinchenko

  Gurobi Staff

  • February 04, 2020 23:44

  Yes, the incumbent (if such is found) will be accessible through 'x' field of you variables.

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  Sam Ganzfried

  • February 05, 2020 01:01

  

  

  

  I just tried an example where model.get(GRB.IntAttr.Status) had a value of 9 (TIME_LIMIT status),

  and when I call get(GRB.DoubleAttr.X)

  I get:

  Exception in thread "main" gurobi.GRBException: Error at GRBVar.get
  at gurobi.GRBVar.get(GRBVar.java:124)

   

   

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  Yuriy Zinchenko

  Gurobi Staff

  • February 05, 2020 23:59

  You should check if the incumbent was found first, before querying for the X property.  You can do this by checking SolCount, https://www.gurobi.com/documentation/9.0/refman/solcount.html#attr:SolCount

  (please see our examples for more illustration in the online doc)

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