[Scip] LP not solved but heuristic called

[Jens Leoff]

Hello Mailinglist,

I implemented a heuristic to update the dual bound of the current node. 
Its timingmask is SCIP_HEURTIMING_AFTERLPLOOP, and it needs to results 
of all the pricingproblems of the last iteration in the pricing loop, as 
well as the LP solution and duals.

For some reason the LP does not get solved for node 175 (see the extract 
from the log file below), but the heuristic is called.
At least I guess the LP was not solved, because there is no output from 
the LP solver, as is the case for other nodes.

This results in the heuristic taking the pricing results of the previous 
iteration, and the old LP solution which is not feasible for the current 
node.

Does anyone know where the trouble might come from?

Thanks

Jens Leoff




   2.5s|   174 |   150 | 10713 |  45.3 |5608k|  73 |  23 |1809 | 784 
|1808 | 819 |   0 |   0 |   0 | 8.183333e+01 |      --      |    Inf
In 'scip_active'..of cons: sequence: [19 >= 2], bound: 1.00000000e+00
In 'scip_prop' of GBBranchingDecisions..

ICHBAS02 basis redimensioning invalidates factorization
IBASIS02 loading of Basis invalidates factorization
starting value = 8.20000000e+01
starting shift = 0.00000000e+00
type |   time |   iters | facts |  shift   |    value
   L  |    0.0 |       0 |   414 | 0.00e+00 | 8.20000000e+01
WDEVEX02 trying refinement step..
  --- checking feasibility and optimality
  --- solve(leave) triggers refactorization
  --- refactorizing basis matrix
  --- leave finished. iteration: 6, value: 8.20066667e+01, shift: 
0.00000000e+00, epsilon: 1.00000000e-16, feastol: 1.00000000e-06, 
opttol: 1.00000000e-07
ISOLVE57 stop: 0, basis status: DUAL (1), solver status: RUNNING (-1)
DSHIFT07 = unshifting ...
  --- maxInfeas: 3.88578059e-16, shift: 0.00000000e+00, leavetol: 
1.00000000e-07
Finished solving (status=OPTIMAL, iters=6, leave=6, enter=0, flips=0, 
objValue=8.20066667e+01)

In 'priceSubproblems' (redCost)..

In 'scip_exec' of HeurLagrangeanDualBound..
globalDualBound: 8.18333333e+01, localDualBound: 8.20066667e+01, 
lagrangeanDualBound: 8.20066667e+01

   2.5s|   175 |   151 | 10719 |  45.0 |5610k|  74 |  38 |1809 | 784 
|1808 | 820 |   0 |   0 |   0 | 8.183333e+01 |      --      |    Inf
In 'scip_deactive'..of cons: sequence: [19 >= 2], bound: 1.00000000e+00
In 'scip_active'..of cons: sequence: [19 < 2], bound: 1.20000000e+01
In 'scip_prop' of GBBranchingDecisions..
In 'scip_exec' of HeurLagrangeanDualBound..

pricing results:
[(sequence: [], -2.22044605e-16), (sequence: [19 >= 2], -1.11022302e-16)]
stack:
[(sequence: [19 < 2], 0xfb7ed0, L: 1.20000000e+01)]

trackLength: 1.19066667e+01

*** Program received signal SIGABRT (Aborted) ***