CODEWITHSUNDEEP
optaplanner
Pravesh Jain
Pravesh Jain

Reputation: 4288

Optaplanner: Reproducible solution

I am trying to solve a problem similar to employee rostering. The problem I am facing is every time I run the solver, it generates a different assignment. This makes it harder to debug why a particular case was picked over another. Why is this the case?

P.S. My assignment has many hard constraint and all of them may not be satisfied (most cases I still see some negative hard score). So my termination strategy is based on unimprovedSecondsSpentLimit. Could this be the reason?

Upvotes: 0

Views: 122

Answers (1)

Geoffrey De Smet
Geoffrey De Smet

Reputation: 27312

Yes, it's likely the termination. OptaPlanner's default environmentMode guarantees the exact same solution at the exact same step (*). But CPU cycles differ a lot from run to run, so that means you get more or less steps per run. Use DEBUG logging to see that.

Use stepCountLimit or unimprovedStepCountLimit termination.

(*) Unless specified otherwise in the docs. Simulated Annealing for example will be different even in the exact same step if used with time bound terminations.

Upvotes: 1

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