I am running an optimization on a machine with 50 cores. When I start the optimization it uses all the cores but over time it uses fewer and fewer cores until after the first 1000 solutions it is using around 3 cores. Is this a known issue?
Optimizer CPU cores usage question
FlexSim 17.2.1
Just a guess, but I bet there are FlexSim processes that have hung up. Check your Windows task manager and see if there are any stuck FlexSim background processes.
I've seen this happen with the Experimenter if the model in one of the replications crashed or otherwise hung during execution.
Or maybe @jordan.johnson has some other ideas.
Do the replications run quickly? One thing I have seen is that, as the number of completed runs increases, OptQuest does more and more sorting/decision making to get the next solution on the list. This means it can't create solutions as fast as the cores could handle them. In general, the first few cores tend to do most of the work.
If the replications take 30 seconds or more to run, this might not be the issue. I would have to dig in deeper, and see if there is a bug.
That makes a lot of sense and seems to be the case. The replications in this case take about 7 seconds each to run. The best workaround I have found is to run multiple instances of FlexSim with subsets of the problem. This seems to more fully utilize the cores and produces a larger solution set in a shorter period of time. Would this be the suggested workaround?
That's quite a clever solution, especially if it works for you. I can't say I have a better one.
8 People are following this question.
