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Subject: [OMPI users] Windows C++ Linker Error "unresolved symbol" for MPI::Datatype::Free
From: Hartman, Todd W. (thartman_at_[hidden])
Date: 2013-02-21 01:20:39

I'm trying to build a simple Open MPI application for Windows. I've installed the binaries for OpenMPI-v1.6.2 (64-bit). I've also installed Visual Studio 2010. The machine(s) are Windows 7 x64.

When I attempt to compile a simple program that uses MPI::Send(), I get a linker error saying that it cannot resolve MPI::Datatype::Free().

Here's a minimal example:

#include <mpi.h>
#include <iostream>
int main( int argc, char** argv ) {

    // Meant to run with 2 processes.
    if (MPI::COMM_WORLD.Get_rank() == 0) {
        int data;
        std::cout << "received " << data << std::endl;
    } else {
        int data = 0xdead;
        std::cout << "sending " << data << std::endl;


When I compile it:

mpic++ send_compile.cpp -o send_compile.exe -DOMPI_IMPORTS -DOPAL_IMPORTS -DORTE_IMPORTS 

Microsoft (R) C/C++ Optimizing Compiler Version 16.00.40219.01 for x64
Copyright (C) Microsoft Corporation.  All rights reserved.

cl : Command line warning D9035 : option 'o' has been deprecated and will be removed in a future release
Microsoft (R) Incremental Linker Version 10.00.40219.01
Copyright (C) Microsoft Corporation.  All rights reserved.

"/LIBPATH:C:\Program Files (x86)\OpenMPI_v1.6.2-x64/lib" 
send_compile.obj : error LNK2001: unresolved external symbol "public: virtual void __cdecl MPI::Datatype::Free(void)" (?Free_at_Datatype@MPI@@UEAAXXZ)
send_compile.exe : fatal error LNK1120: 1 unresolved externals

This program compiles and runs without complaint on an Ubuntu machine around here. I don't know what the problem is. Open MPI's documentation didn't say anything about adding the CPP defines (OMPI_IMPORTS, OPAL_IMPORTS, ORTE_IMPORTS) whose absence were causing other linker errors similar to this. Google found some items in the mailing list archive. I cannot find any information about this particular problem, though.

I tried using dumpbin to get symbols that were in the .lib files installed by MPI, but didn't find any reference to that function name. I didn't find any answers looking in the MPI headers, either.

I have a similar program in C that compiles and runs fine on this Windows machine. I don't know what I'm doing wrong with C++. Can someone point me in the right direction? Is there some documentation regarding getting things to work on Windows? The release notes don't address this problem, and I can't find any other documentation related to what might be different from *nix to Windows (WRT to Open MPI).



P.S. This is copied from a StackOverflow question I posted ( Forgive the cross-posting.