[Bug-glpk] Re: glpsol crash

[Andrew Makhorin]

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

> Also, but that's a different story, I wonder that the Cbc stand-alone
> solver from the COIN-OR project could solve the same instance in less
> than half a minute. I didn't expect the difference in running time to be
> greater than a factor of perhaps 10 or 20, clearly not >600. Aren't both
> using somewhat similar branch-and-cut techniques?

Success/failure of the branch-and-cut method heavily depends on the cut 
generators used. In this sense coin-cbc is more powerful than glpk, especially
for mip instances having non-binary variables like yours.