Originally posted by: SystemAdmin

[billdoors said:]

I need to call cplex.solve() several times to solve models with same constraints and different objective function.
ie,

IloModel model(env);
model.add(constraints);

for(i = 0; i<10;i++)<br />{
IloObjective obj;
IloMinimize(env,expr);   //where expr here is IloExpr and updated at each loop
model.add(obj);
IloCplex cplex;
cplex.extract(model);
cplex.solve();

expr.end();
obj.end();
cplex.end();

}



But after only 2 or 3 times or the loop, error was thrown "out of memory". I destruct cplex each time at the end of the loop.

also each time, there is message like "mip start values provide initial solution with objective *". But according to my understanding, cplex is destruct at the end of the loop, why there is a "provide initial solution"

thank you so much for answering my questions.

below is the screen print


Presolve has eliminated 50 rows and 0 columns...
Presolve has improved bounds 117649 times...
Tried aggregator 1 time.
MIP Presolve eliminated 50 rows and 0 columns.
MIP Presolve modified 352947 coefficients.
Reduced MIP has 701093 rows, 237797 columns, and 1637531 nonzeros.
Presolve time =   14.88 sec.
Clique table members: 232897.
MIP emphasis: balance optimality and feasibility.
Root relaxation solution time =    2.02 sec.


MIP start values provide initial solution with objective 0.0000.
Presolve has eliminated 50 rows and 1 columns...
Presolve has improved bounds 117649 times...
Tried aggregator 1 time.
MIP Presolve eliminated 50 rows and 1 columns.
MIP Presolve modified 352947 coefficients.
Reduced MIP has 701093 rows, 237797 columns, and 1637531 nonzeros.
Presolve time =   14.69 sec.
Clique table members: 232897.
MIP emphasis: balance optimality and feasibility.
Root relaxation solution time =   15.10 sec.
t_k = 92.5228
this is the objective value 0

MIP start values provide initial solution with objective 9067.2310.
Presolve has eliminated 50 rows and 1 columns...
Presolve has improved bounds 117649 times...
Tried aggregator 1 time.
MIP Presolve eliminated 50 rows and 1 columns.
MIP Presolve modified 352947 coefficients.
Reduced MIP has 701093 rows, 237797 columns, and 1637531 nonzeros.
Presolve time =   14.37 sec.
Clique table members: 232897.
MIP emphasis: balance optimality and feasibility.
Root relaxation solution time =   40.16 sec.
t_k = 20.3099
this is the objective value -36268.9

[b]MIP start values provide initial solution with objective 5528.7994.[/b]
Presolve has eliminated 50 rows and 1 columns...
Presolve has improved bounds 117649 times...
Tried aggregator 1 time.
MIP Presolve eliminated 50 rows and 1 columns.
MIP Presolve modified 352947 coefficients.
Reduced MIP has 701093 rows, 237797 columns, and 1637531 nonzeros.
Presolve time =   16.27 sec.
Clique table members: 232897.
MIP emphasis: balance optimality and feasibility.
Root relaxation solution time =   21.29 sec.
t_k = 16.9108
this is the objective value -784.82

[b]MIP start values provide initial solution with objective 7726.3818.[/b]
Presolve has eliminated 50 rows and 1 columns...
Presolve has improved bounds 117649 times...
Tried aggregator 1 time.
MIP Presolve eliminated 50 rows and 1 columns.
MIP Presolve modified 352947 coefficients.
Reduced MIP has 701093 rows, 237797 columns, and 1637531 nonzeros.
Presolve time =   14.74 sec.
Clique table members: 232897.
MIP emphasis: balance optimality and feasibility.
Root relaxation solution time =   62.57 sec.

       Nodes                                         Cuts/
  Node  Left     Objective  IInf  Best Integer     Best Node    ItCnt     Gap
      Variable B Parent  Depth

     0     0    -6087.4621   528     7726.3818    -6087.4621   121382  178.79%
    0+    0                   0    -4494.8512    -6087.4621   121382   35.43%
                -6081.6960   371    -4494.8512   Fract:  200   121430   35.30%
                -6078.9265   195    -4494.8512   Fract:  200   121460   35.24%
*     0+    0                   0    -5538.4781    -6078.9265   121460    9.76%
*     0+    0                   0    -6028.5906    -6078.9265   121460    0.83%
*     0+    0                   0    -6045.1287    -6078.9265   121460    0.56%
*     0+    0                   0    -6062.1142    -6078.9265   121460    0.28%
*     0+    0                   0    -6064.0445    -6078.9265   121460    0.25%

Gomory fractional cuts applied:  9
Concert exception caught: CPLEX Error  1001: Out of memory.


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