Re: [Bug-glpk] [Fwd: Inconsistent run times]

[Xypron]

Hello Marc,

your mail had to be forwarded manually because you are not subcribed
to the GLPK bug list, see
https://lists.gnu.org/mailman/listinfo/bug-glpk

Are solving the same problem in each round?
What time does glpsol need to solve your second problem?

Best regards

Xypron


On 30.10.2012 20:20, Andrew Makhorin wrote:
> -------- Forwarded Message --------
> Subject: Inconsistent run times
> Date: Tue, 30 Oct 2012 14:34:06 -0400
>
> I am running glpk 4.44 downloaded from sourgeforge for 64-bit windows
> I am writing a problem formulation to an LP file and then reading it 
> into glpsol and also read it from my compiled program.
> I am using Visual Studio 2010 to compile my 64-bit program.
> I have observed the following inconsistencies
>
> The first time a problem is imported and solved (it is a mip 
> formulation) it runs about as fast as using glpsol.
> The following times, the run times are 10 to 12 times LONGER (e.g. 1.2 
> seconds first time, 14.2 seconds thereafter)
> In my program I am timing only the mipopt call, not reading the lp file.
>
> Sequence of calls
>
> create problem
> read lp file
> mipopt with presolve
> destroy problem
>
> repeat the above sequence
>
> The problem is destroyed and the corresponding glpk pointer is null 
> between iterations.
> However the glpk library is not unloaded between repeats of this sequence
> When my program is restarted the sequence of events repeats, i.e. only 
> the first time are the run times short.
>
> Formulation is ultimately solved and no error codes are return (i.e. 
> solution is reported as primal optimal which it is)
>
> I have repeated this behavior on several different Windows 7 machines.
>
>
>
>
>
>
>
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