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[Bug-glpk] [Fwd: Inconsistent run times]
From: |
Andrew Makhorin |
Subject: |
[Bug-glpk] [Fwd: Inconsistent run times] |
Date: |
Tue, 30 Oct 2012 23:20:29 +0400 |
-------- Forwarded Message --------
From: Marc Goetschalckx <address@hidden>
To: address@hidden
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.
- [Bug-glpk] [Fwd: Inconsistent run times],
Andrew Makhorin <=