On 3/25/20 8:23 PM, Andrew Makhorin wrote:
-------- Forwarded Message --------
From: "Sierra Ansuas, Juan Pablo" <[email protected]>
To: [email protected] <[email protected]>
Cc: [email protected] <[email protected]>, "Di Cristofaro, Milton Nadir" <MDiCristo
[email protected]>
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
