Re: [Bug-glpk] Memory allocation problem

[xypron]

Hello Pietro,

thank you for your post. The essential line in the output is:
xmalloc: no memory available

The memory size needed for your model depends does not directly depend on
the number of
columns and rows but on the number of non zeroes. For each non zero a
structure GLPAIJ as
defined in src/glpapi.h is needed.

On a 32 bit system the size of the structure is 8 + 6 * 4 = 32 bytes, on a
64 bit system
8 + 6 * 8 = 56 bytes.

The memory limits per process for Windows are described at
http://msdn.microsoft.com/en-us/library/aa366778%28VS.85%29.aspx

My expectation for 342 370 binaries is that you will not be able reach an
integer solution
with a brute force approach.

One way to address such a big problem is to use column generation. 

Guy Desaulniers ed., "Column Generation", 2005
is a valuable book on this theme.

Best regards

Xypron



Pietro Scionti wrote:
> 
> Hi everyone,
> I have been using GLPK for almost a year now to solve integer optimization
> problems quite satisfactorily, but I'm now encountering a serious problem.
> The model I'm trying to solve has 342 370 columns (variables are
> 3-dimensional, in the form of 134 operators x 7 work shifts x 365 days),
> all of them binary, and I fear an even bigger number of rows which I'm not
> able to count. When I try to run GLPK (through command line) I get the
> following log:
> 
> GLPSOL: GLPK LP/MIP Solver 4.41
> Parameter(s) specified in the command line:
>  -m agente.txt -d dati_agente.txt -o out_agente_mipgap100000.txt --mipgap
> 100000 --log log_mipgap100000.txt
> Reading model section from agente.txt...
> agente.txt:90: warning: final NL missing before end of file
> 90 lines were read
> Reading data section from dati_agente.txt...
> dati_agente.txt:24: warning: final NL missing before end of file
> 24 lines were read
> Generating Turninelgiorno...
> Generating RiposiFissiPrimi6Blocchi...
> Generating RiposiFissiUltimoBlocco...
> Generating FabbisogniTurniNotturniPerGiorno...
> Generating NoNotturnoPrimaDiRiposo...
> Generating StessiNotturniTraOperatori...
> Generating StessiNotturniSingoliTraOperatori...
> Generating StessiNotturniSingoliOgniOperatore...
> Generating DistanzaMinimaTraNottiPerAgenti...
> Generating assegnazioni...
> Model has been successfully generated
> xmalloc: no memory available
> Error detected in file ..\src\glplib07.c at line 72
> 
> And a pop-up tells me that "The exception unknown software exception
> (0x40000015) occurred in the application at location 0x10034999.". I'm not
> able to debug this myself.
> 
> Note that this has been transcribed by me reading the prompt since that
> error prevents the creation of the log itself.
> I managed to make it work setting the days count to 49; 6 months gave me
> the same treatment.
> I got this both on a Pentium 4 2.40 GHz with 2 GB of RAM and on a Core2
> Duo E8400 3 GHz with 4 GB of RAM, running XP Professional SP 3.
> 
> Thanks
> Pietro
> 
> PS: I think this is the right newsletter, but if you'd rather have me post
> it on 'help' just tell me
> 
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