[Cbc] Bad behavior on unitcal_7 - hangs before exiting

[John Forrest]

Haroldo,

Maybe not an infinite loop, but ... took several hours to finish.

Can't see the use of entering that bit of code near CbcModel.cpp:5254 as 
code expects problem to be infeasible and does not do much with solution 
if solve finds to be feasible on second try.

So I have stopped solve.

John

On 20/01/17 23:16, Haroldo Gambini Santos wrote:
>
> 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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