[Cbc] Bad behavior on unitcal_7 - hangs before exiting

[Haroldo Gambini Santos]

Hi,

My tests with unitcal_7 from miplib are indicating a problematic 
behavior with this instance.  (compiled with Blas, Lapack,  -O2 -g, 
tested with G++ 6.2 and 6.3)

Running

cbc unitcal_7.mps.gz seco 1000 heur off solve

Makes CBC to enter an infinite loop at the end of the search.

Cbc0020I Exiting on maximum time
Cbc0005I Partial search - best objective 1e+50 (best possible 19567132), 
took 769793 iterations and 302 nodes (999.95 seconds)
Cbc0032I Strong branching done 3706 times (218262 iterations), fathomed 
0 nodes and fixed 0 variables
Cbc0035I Maximum depth 47, 0 variables fixed on reduced cost
*[stays here forever]*

Checking which part of the code was executing, I found the following 
backtrace:

#0  0x00007f4652584414 in ClpPrimalColumnSteepest::saveWeights 
(this=0xb9989c0, model=<optimized out>, mode=<optimized out>)
     at ClpPrimalColumnSteepest.cpp:3094
#1  0x00007f46525f6513 in ClpSimplexPrimal::statusOfProblemInPrimal 
(this=this at entry=0xc3778b0, lastCleaned=@0x7fffa5be077c: 0,
     type=type at entry=1, progress=progress at entry=0xc377e28, 
doFactorization=doFactorization at entry=true, 
ifValuesPass=ifValuesPass at entry=0,
     originalModel=0x0) at ClpSimplexPrimal.cpp:1636
#2  0x00007f46525fa773 in ClpSimplexPrimal::primal 
(this=this at entry=0xc3778b0, ifValuesPass=0, ifValuesPass at entry=1,
     startFinishOptions=startFinishOptions at entry=0) at 
ClpSimplexPrimal.cpp:361
#3  0x00007f46525ac368 in ClpSimplex::primal (this=this at entry=0xc3778b0, 
ifValuesPass=ifValuesPass at entry=1,
     startFinishOptions=startFinishOptions at entry=0) at ClpSimplex.cpp:5971
#4  0x00007f4652aeabd4 in OsiClpSolverInterface::initialSolve 
(this=0x9d1acf0) at OsiClpSolverInterface.cpp:648
#5  0x00007f46530e68d1 in CbcModel::branchAndBound 
(this=this at entry=0x131c7b0, doStatistics=doStatistics at entry=0) at 
CbcModel.cpp:5254
#6  0x00007f46533e473d in CbcMain1 (argc=argc at entry=7, 
argv=argv at entry=0x7fffa5be82d8, model=...,
     callBack=callBack at entry=0x7f46533c7b50 <dummyCallBack(CbcModel*, 
int)>, parameterData=...) at CbcSolver.cpp:6817
#7  0x00007f46533fba9a in CbcMain1 (argc=argc at entry=7, 
argv=argv at entry=0x7fffa5be82d8, model=...,
     callBack=callBack at entry=0x7f46533c7b50 <dummyCallBack(CbcModel*, 
int)>) at CbcSolver.cpp:1295
#8  0x00007f46533fbaac in CbcMain1 (argc=argc at entry=7, 
argv=argv at entry=0x7fffa5be82d8, model=...) at CbcSolver.cpp:1163
#9  0x0000000000400c4a in main (argc=7, argv=0x7fffa5be82d8) at 
CoinSolve.cpp:336
(gdb)


-- 
==================================================
Haroldo Gambini Santos
D.Sc, Computer Science
Universidade Federal de Ouro Preto
http://www.decom.ufop.br/haroldo/

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