Gurobi stuck after solution found

進行中

Jingyuan Hu

2022年08月02日 23:29

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Hi, 

I am currently working on a large-scale mixed-integer programming problem and I set the optimality gap to 1%. However, I got the following outputs

 

This is weird because I had a similar problem before and gurobi has no problem solving it (took 2 hours), but for this instance it got stuck for about 3 hours even though the gap is already 0.12%, which is lower than 1%. I wonder why this is happening and is there anything I can do to speed it up?

 

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  Matthias Miltenberger

  • Gurobi Staff

  2022年08月03日 09:42

  Hi!

  This is a pretty large problem instance and Gurobi performs a lot of presolving reductions to reduce its size. After the final solution is found, these reductions need to be reverted to compute a solution for the original space and this could take some time. It should still only take a fraction of the presolving time to perform that transformation, though.

  Let's further inspect this issue in an internal ticket.

  Best regards,
  Matthias

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