The system is a micro-OS running in an embedded processor. There will be multiple of these processors, each one with a single mpi rank. I'm starting to think that I will have to do what Hydra does myself. Is there any documentation about what a mpi job expects from hydra? Eduardo On Sat, Jan 17, 2015 at 5:58 PM, Jeff Hammond <[email protected]> wrote:

How do you create processes on this system? If you are using an MPI implementation that has a 1:1 mapping between MPI processes and OS processes, you've got to be able to create multiple processes somehow.

Do you have any platform details you can share?

Jeff

On Sat, Jan 17, 2015 at 11:46 AM, Eduardo <[email protected]> wrote:

...

I tried to use a newer MPICH, but, as you said, Hydra forks as part of mpiexec. Is it possible to launch a job without mpiexec/mpirun ? That should probably work in my environment (assuming that there is no listener as a heavy process as it is the case in the default mpich-1.2.7p1).

The problem is not that the fork symbol is missing. The problem is that it is been called. My environment actually has a dummy fork, but that only causes the program to abort if it is called.

So in summary, the problem is that I cannot use mpiexec to launch a program, because it calls fork. In mpich-1.2.7p1 , I can launch myself the program as if I was launching a debug (as in section 3.5.6 of the CH_P4 manual). In addition, the mpich cannot issue a fork for a listener like task, only threads.

Eduardo

On Sat, Jan 17, 2015 at 4:23 PM, Jeff Hammond <[email protected]> wrote:

...

MPICH shouldn't fork. Hydra probably uses fork to launch processes as

part

...

of mpiexec.

Blue Gene doesn't support fork either and MPICH runs there, but the process launcher is not Hydra. Same for Cray last time I checked. So I'm sure that fork isn't required to use MPICH, at least if dynamic processes are not used.

Is the issue that you cannot link an MPI program because the fork symbol is missing or that you cannot launch jobs with a Hydra?

All mainstream MPI implementations use OS processes to implement MPI processes, but the standard doesn't require this. FG-MPI uses threads to implement MPI processes, but as it still uses Hydra (AFAIK), it may or may not work for you.

Can you describe in detail what happens when you try to build and run MPICH-latest on your system?

Jeff

Sent from my iPhone

On Jan 17, 2015, at 9:41 AM, Eduardo <[email protected]> wrote:

I would use a newer version if I could. However, I cannot issue a fork in my embedded environment. I can create threads though.

So, is there any newer versions of mpich that does not create heavy processes? I can live without MPI_Spawn and the like.

Regards,

Eduardo

On Jan 16, 2015 5:42 PM, "Wesley Bland" <[email protected]> wrote:

...

Can you try using a more recent version of MPICH. The version you are using is years old and we don't support it anymore. Our latest version

is

...

3.1.3. You might see if the issue is still present there.

Thanks, Wesley

On Fri, Jan 16, 2015 at 10:54 AM, Eduardo <[email protected]> wrote:

...

Hi,

I am trying to compile and use mpich-1.2.7p1 with threaded listener (i.e. configured with --enable-threaded-listener). However, I cannot

even

...

run a simple mpi example with the resulting mpich.

I need to use threaded listener because the environment I am compiling for (kind of embedded environment) does not have fork (no heavy processes).

The error I get with the mpich with threaded listener is:

rm_2889: 1103279872: p4_error: listener select: -1 p4_error: latest msg from perror: Bad file descriptor p0_2710: (2.097656) net_recv failed for fd = 5 p0_2710: 3778266880: p4_error: net_recv read, errno = : 104

Has anyone experienced a similar problem?

Thanks in advance, Eduardo

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