[SCIP] possible memory leak in SCIP with JuMP Interface

[Yankai Cao]

Hi, 

I am using scipoptsuite-4.0.0 with julia interface SCIP.jl. I  find that if I create and solve models in a for loop using SCIP with models built with JuMP, then the peak memory usage increases dramatically as the number of iterations increases. I would expect the peak memory usage keeps almost constant.

Here is the test code test.jl: 

using JuMP, Gurobi, SCIP
function test(iter)
for i = 1:iter
     m= Model()
     nvar = 1000
     @variable(m, 0<=x[1:nvar]<=1)
     @constraint(m, con[i in 1:(nvar-2)], x[i]+x[i+1]<=1)
     @objective(m, :Min, sum{(x[i]+x[i+2])^2, i in 1:(nvar-2)})
     m.solver=SCIPSolver("display/verblevel", 0)
     #m.solver=GurobiSolver(LogToConsole=0,OutputFlag=0)
     solve(m)
end
end
test(10)


I monitored the peak memory usage using /usr/bin/time -v julia test.jl
For SCIP, I got 
test(1) 
Maximum resident set size (kbytes): 234312
test(10)
Maximum resident set size (kbytes): 803168
test(100)
Maximum resident set size (kbytes): 6441800

For Gurobi, I got
test(1) 
Maximum resident set size (kbytes): 174972
test(10)
Maximum resident set size (kbytes): 187388
test(100)
Maximum resident set size (kbytes): 263780

So for Gurobi, the result is as expected, but for SCIP the peak memory usage do increases dramatically. Can anyone check this issue? Thanks.





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