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Re: [Bug-glpk] [Fwd: Inconsistent run times]
From: |
Xypron |
Subject: |
Re: [Bug-glpk] [Fwd: Inconsistent run times] |
Date: |
Tue, 30 Oct 2012 20:44:00 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:10.0.9) Gecko/20121014 Icedove/10.0.9 |
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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>