CODEWITHSUNDEEP
optaplanner
AndreasC
AndreasC

Reputation: 1

OptaPlanner immediately produces better solution after terminating and restarting the solver

I created a solution based on the task assigning example of OptaPlanner and observe one specific behavior in both the original example and my own solution:

Solving the 100tasks-5employees problem does hardly produce new better scores after half a minute or so, but terminating the solver and restarting it again does immediately bring up better solutions.

Why does this happen? In my understanding the repeated construction heuristic does not change any planning entity as all of them are already initialized. Then local search is started again. Why does it immediately find new better solutions, while just continuing the first execution without interruption does not or at least much slower?

Upvotes: 0

Views: 194

Answers (1)

Geoffrey De Smet
Geoffrey De Smet

Reputation: 27312

By terminating and restarting the solver, you're effectively causing Late Acceptance to do a reheating. OptaPlanner will do automatic reheating once this jira is prioritized and implemented.

This occurs on a minority of the use cases. But if it occurs on a use case, it tends to occur on all datasets.

I've some cases workaround it by configuring multiple <localSearch> phases with <unimprovedSecondsSpentLimit> terminations, but I don't like that. Fixing that jira is the only real solution.

Upvotes: 2

Related Questions