I struggle now with several issues with JSprit.
We found out that solution is not always, even not more likely to by optimal, or best ever. In fact we try calculate one VRP several times, with true Random from java utils and got several solutions. Some of them was excelent, some horrible. But the problem is, that we cannot tell if the solution provided by JSprit is good enough. Diferences between solutions can be almost 30%, so it must be considered.
The result from this is, that if we provide “true” random, it can start the optimisation from random point in space, thus found out best ever solution faster, but it’s random. Next run can end with totaly diffrent result, most likely worse.
I’m currently testing new idea with static seed, but bigger iteration threshold. My idea is, that if JSprit got enough time to search through a space, it can found out better solution. The result seems promissing, but what I doesn’t expect is that even with static seed I got different solutions after long run (cca 3000 iterations) for same problem. So calculations are not replicable, even with static seed.
Have someone any experience with this behavior?
Does anyone observe weird behavior in iteration phase wich changing performace from 1 thread to full thread count from setup? Like I have 15 threads for interations. But it repetitively drops from 15 to 1, then go to 15 again. I don’t know what this means, or where to look.