[Bug-glpk] Re: glpsol crash

[Tobias Gödderz]

On So, 2010-10-10 at 23:54 +0400, Andrew Makhorin wrote:
> > I'm trying to solve a MIP with glpsol; it crashed, the last few lines in
> > the log were
> > 
> > +2268089: mip =   9.717500000e+04 >=   9.128300000e+04   6.1% (271264;
> > 14832)
> > glp_malloc: memory limit exceeded
> > Error detected in file glpenv05.c at line 65
> > 
> > I quoted part of the log file below.
> 
> This is not a bug. Your mip instance is hard for glpk mip solver, and 
> since the best bound selection technique is used by default, the solver
> failed due to insufficient memory.

I expected the abort due to insufficient memory. I didn't expect the
line "Error detected in file glpenv05.c at line 65", and glpsol didn't
write anything in the file specified with --output, which it usually did
when it hit the memory limit.

> (Btw, --first is not a good choice for
> branching; try --drtom or --pcost.)

I experimented with several options, starting with the default ones, and
aborted the runs when glpsol didn't find a feasible solution after 10
minutes. I supposed that the one found early with --first was due to
chance, but sticked with it for this instance nevertheless. But I can't
remember trying --pcost, I'll give it a try.

Apropos, is it possible to specify a starting solution? I couldn't find
anything about that.

Thanks for the help,

Tobias

-- 
open STDOUT, "|-"
    and print "uJa tsonrehtP  lreahrekc"
    or  print pack "nN"x4, unpack "vV"x4, <STDIN>