Re: [Fwd: Possible bug in GLPK - Error detected in file env/alloc.c at line 72]

[Heinrich Schuchardt]

On 3/25/20 8:23 PM, Andrew Makhorin wrote:
> -------- Forwarded Message --------
> From: "Sierra Ansuas, Juan Pablo" <address@hidden>
> To: address@hidden <address@hidden>
> Cc: address@hidden <address@hidden>, "Di Cristofaro, Milton Nadir" <MDiCristo
> address@hidden>
> Subject: Possible bug in GLPK - Error detected in file env/alloc.c at
> line 72
> Date: Wed, 25 Mar 2020 18:34:56 +0000
>
> > Dear GLPK mantainer(s),
> >
> > I am having problems when trying to run the GLPK solver in a multi-
> > threaded fashion using its C API and OpenMP. While the solver does
> > appear to work, an error comes up when trying to free the memory with
> > glp_delete_prob:
> >
> > glp_free: memory allocation error
> > Error detected in file env/alloc.c at line 72
> >
> > I am no GLPK expert but I would be very grateful if you could check
> > the provided source code and determine whether this is being caused
> > by a bug or a simple beginner mistake.
> >
> > Running on an eight core processor, 8GiB ram. Stack size limit: 2GB
> > (ulimit -s 2000000), Stack size limit per thread: 200MB (export
> > OMP_STACKSIZE=200000). Provided source makes little sense but is
> > quite short and reproduces the problem every time. Compile command is
> > as follows:
> >
> > gcc test_c.c  -o test_c -fopenmp -I/home/user/libglpk/glpk-
> > 4.65/include /home/user/libglpk/glpk-4.65/src/.libs/libglpk.so.40.3.0
> >
> >
> > Regards,
> >
> > Juan Pablo Sierra

Hello Juan,

Did you compile GLPK with '--enable-reentrant=yes'?

You are creating all problems in one thread and then call the solver in
separate threads. This is not supported by GLPK.

Please, have a look at:
glpk-4.65/examples/threads/multiseed.c

Here all GLPK library calls needed for each individual model are called
within the same separate thread.

Please, have a look at the error and output handling in the example too.

Best regards

Heinrich