number of threads in solution pool method
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Dear Gurobi Community members,
I am using the pool solution to find all feasible solutions of my milp model (setting the PoolSolutions parameter to its max). I also set the thread number to the number of threads on my laptop. Although all of the threads are involved at the beginning of the solution pool completion phase, after a while involved threads reduces to one!
Is it the gurobi limitation that cannot use multithreading during solution pool completion process?
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Hi Akram,
There is no guarantee that Gurobi is going to utilize all available cores at all times during the solving process. It is fairly common that especially during the beginning and the end, there simply is not enough work to distribute among the cores/threads.
Cheers,
Matthias0 -
Dear Matthias,
Thanks for your reply. Actually I have a big model which takes some days to be solved. I also have worked with gurobi to solve such big models without using solution pool and monitored its resource consumption (RAM and CPU). Although, as you have noted, CPU is not fully utilized at the beginning and the end of process, but in the middle it is(not to say all the cores but most of them are engaged).
The problem is that when I try to solve my model using solution pool, finding the first optimum solution as well as the first part of solution pool completion utilizes most of the cores, however it switches to single thread mode very soon (e.g. after 4 hours in a model which takes 10 days to be solved including solution pool completion).
Do you have any idea about this observation?
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