memory leak in MixedIntegerLinearProgram coin backend

[dimpase]

As reported here; running the following in a loop leads to memory growth.

def get_polytope():
    q = MixedIntegerLinearProgram(maximization=False, solver='Coin')
    w = q.new_variable(real=True, nonnegative=True) 
    q.add_constraint(w[0]==0)

def fill_memory(n):
    for i in xrange(n):
        P = get_polytope()

sage: get_memory_usage()
288.58984375
sage: fill_memory(2000); get_memory_usage()
300.5859375
sage: fill_memory(2000); get_memory_usage()
302.5859375
sage: fill_memory(2000); get_memory_usage()
303.5859375
sage: fill_memory(2000); get_memory_usage()
305.5859375

This appears to be coin-specific.

CC: @mkoeppe

Component: linear programming

Issue created by migration from https://trac.sagemath.org/ticket/21825

[seblabbe]

comment:2

Importing the description from #21826. A little bit simplified version of code causing the leak.

[mkoeppe]

This will be solved by:

• Deprecate sage_numerical_backends_coin in favor of cvxpy+cylp, upgrade cbc to 2.10.10 #35368