Originally posted by: PhilippH.

Hello everyone,

I am trying to start a distributed parallel MIP optimization on our cluster system (CPLEX 12.6.2, Unix, MPI) via MATLAB, but after successfully creating the Cplex object, I keep getting the CPLEX error 1814 "Failed to load dynamic library" (CPXERR_DYNLOAD) while or shortly after reading the .vmc file.

Can anyone tell me which dynamic libraries this error refers to and what I need to do to fix it?

Help would be much appreciated,

Philipp

The error refers to one of the .so files in the cplex/bin/x86-64_linux directory. What MPI library and what version of the library are you using? What is the command line you use to launch mpirun? I take it your matlab process is one of processes spawned by mpirun?

Originally posted by: PhilippH.

Listed below are the MPI version and libraries:

/usr/mpi/gcc/openmpi-1.4.2/bin/mpirun

[user@donar ~]$ ldd /usr/mpi/gcc/openmpi-1.4.2/bin/mpirun
        libopen-rte.so.0 => /usr/mpi/gcc/openmpi-1.4.2/lib64/libopen-rte.so.0 (0x00002b6ab221e000)
        libopen-pal.so.0 => /usr/mpi/gcc/openmpi-1.4.2/lib64/libopen-pal.so.0 (0x00002b6ab2468000)
        libdl.so.2 => /lib64/libdl.so.2 (0x0000003334000000) 
        libnsl.so.1 => /lib64/libnsl.so.1 (0x0000003336c00000) 
        libutil.so.1 => /lib64/libutil.so.1 (0x0000003341200000)
        libm.so.6 => /lib64/libm.so.6 (0x0000003333c00000)
        libpthread.so.0 => /lib64/libpthread.so.0 (0x0000003334400000)
        libc.so.6 => /lib64/libc.so.6 (0x0000003333800000)
        /lib64/ld-linux-x86-64.so.2 (0x0000003333400000)

glibc Version : glibc-2.5-49.el5_5.7

In our case, CPLEX is started from the MATLAB environment. Also, the CPLEX tuning process succesfully runs before the solving process begins and the error occurs.

The attached screenshot shows the necessary files we might need, located in the .../CPLEX_Studio1262/cplex/bin/x86-64_linux folder.

First of all, the OpenMPI version officially supported by CPLEX on Linux is 1.6, so you may have to upgrade your MPI installation.

Second, none of this is going to work unless you start matlab through mpirun as well. For MPI, all processes participating in the communication must be started through mpirun (maybe check the OpenMPI manuals). In particular, at the start of you matlab code you must somehow call MPI_Init(). Are you doing that?

What exactly is the mpirun command you are using to fire up your MPI universe?

Originally posted by: PhilippH.

First of all, thank you for further looking into our problem.

After some digging I found out that our MPI universe is actually started within MATLAB by the following command lines:

Before the mpiexec command, Intel's SMPD is launched:

I have not found the MPI_Init() in MATLAB yet.

Maybe MPI_Init() is invoked implicitly on matlab startup if you invoke matlab like this? Could you check with a matlab/MPI export on your site?