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Re: [Help-glpk] Too much Memory consumption in GLPK 4.36

From: Andrew Makhorin
Subject: Re: [Help-glpk] Too much Memory consumption in GLPK 4.36
Date: Tue, 24 Feb 2009 08:11:24 +0300

> I am using GLPK 4.36 to solve MIP problem. My problem contains approx.
> 1700 integer variables. I ran GLPK with a timeout of 1 hour and it
> provided a sub-optimal integer solution.

> Then I ran the same problem with timeout of 5 hours. but after around
> 2 hours of run, it crashed, saying that malloc isĀ un-able to allocate
> memory. And when I saw the logs, it consumed around 2 GB memory just
> before crash.

> I suppose that, this is due to a potential memory leak.

No, I do not think so.

>  ( or this is
> because the size of the problem is very big so the data structures
> consumed this much memory ?)

Your mip instance seems to be hard for the glpk mip solver, and the
memory was spent to store components of the search tree (it must be
huge due to the best bound branching heuristic used by default).

To decrease the memory loadness you could try passing the option
'--bestp' or '--dfs' to glpsol. Also you could enable using cutting
planes, for example, with the option '--mir'.

If you wish, you can write your model in mps or cplex lp format,
gzip it and post it to me (*not* to the list). This would allow me to
say something more reasonable.

Andrew Makhorin

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