Hi,

I now tried using --enable-opal-multi-threads (I added an "s" in the end, since "--enable-opal-multi-thread" was not recognized by the configure script).

However, my test code still hangs in the same way as before.

To be clear, I now configure like this:
./configure --enable-mpi-thread-multiple --enable-opal-multi-threads

but the problem remains: MPI_Init_thread still hangs when trying to run the test case with -np 2.

Any other ideas?
Are there other configure options that must be used together with --enable-mpi-thread-multiple to make it work?

Best regards,
Elias


Quoting Ralph Castain <r...@open-mpi.org>:

Hmmm...well, your code runs fine for me:

Ralphs-iMac:mpi rhc$ mpirun -n 2 ./thread_init
Calling MPI_Init_thread...
Calling MPI_Init_thread...
MPI_Init_thread returned, provided = 3
MPI_Init_thread returned, provided = 3
Ralphs-iMac:mpi rhc$

I think the key, however, is that you also have to configure with --enable-opal-multi-thread.


On Jun 16, 2013, at 8:54 AM, Elias Rudberg <elias.rudb...@it.uu.se> wrote:

Hello!

I would like to report what seems to be a bug in MPI_Init_thread in OpenMPI 1.7.1.

The bug can be reproduced with the following test program (test_mpi_thread_support.c):
===========================================
#include <mpi.h>
#include <stdio.h>
int main(int argc, const char* argv[]) {
 int provided = -1;
 printf("Calling MPI_Init_thread...\n");
 MPI_Init_thread(NULL, NULL, MPI_THREAD_MULTIPLE, &provided);
 printf("MPI_Init_thread returned, provided = %d\n", provided);
 MPI_Finalize();
 return 0;
}
===========================================

When trying to run this when OpenMPI was configured with --enable-mpi-thread-multiple, the program hangs when trying to run using anything more than one process.

Steps I use to reproduce this in Ubuntu:

(1) Download openmpi-1.7.1.tar.gz

(2) Configure like this:
./configure --enable-mpi-thread-multiple

(3) make

(4) Compile test program like this:
mpicc test_mpi_thread_support.c

(5) Run like this:
mpirun -np 2 ./a.out
Then you see the following two lines of output:
Calling MPI_Init_thread...
Calling MPI_Init_thread...
And then it hangs.

MPI_Init_thread did not hang in earlier OpenMPI versions (for example it worked in 1.5.* and 1.6.*), so it seems like a bug introduced in 1.7.

The description above shows how I reproduce this in Ubuntu on my local desktop computer, but the same problem exists for the OpenMPI 1.7.1 installation at the UPPMAX computer center where I wan to run my code in the end. I don't know all details about how they installed it there, but I know they set --enable-mpi-thread-multiple. So maybe it hangs in 1.7.1 on any computer as long as you use MPI_THREAD_MULTIPLE. At least I have not seen it work anywhere.

Do you agree that this is a bug, or am I doing something wrong?

Best regards,
Elias


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