[mpich-discuss] MPI_Comm_spawn_multiple Segment fault

[Wesley Bland]

You're probably just running out of resources. 90 processes (not threads) on one node is a lot. A common use of MPI is to have one (or a few) processes per node and if you need more local instances, you investigate using additional threads (such as OpenMP).

Thanks,
Wesley

On Sep 26, 2013, at 9:45 PM, myself <chcdlf at 126.com> wrote:

> I'm trying to spawn several processes on two node. When the number of child processes is small, it works fine, such as less than 80. However, when I tried to spawn 90+ processes, mpirun told me "Segmentation fault (core dumped)". Is something I did wrong or I didn't do?
> 
> My MPICH compile command: 
> 
> $ ./configure --prefix=/opt/mpich3 --with-device=ch3:nemesis --with-pm=hydra --enable-fast=none --enable-g=dbg CFLAGS=-fPIC --disable-f77 --disable-fc
> 
> Here is my source code:
> 
>  #include "mpi.h"
>  #include <stdio.h>
>  #include <stdlib.h>
>  #include <unistd.h>
> 
>  int main( int argc, char *argv[] ) {
> 
>      int HLEN=2;
>      char *host[]={"node1","node2"};
>      char name[65];
> 
>      int count;
>      if(argc==2)
>          count=atoi(argv[1]);
>      else
>          count=2;
> 
>      int root=0;
>      char* array_of_commands[count];
>      int array_of_maxprocs[count];
>      int errcodes[count];
>      MPI_Info array_of_info[count];
>      MPI_Comm parentcomm, intercomm;
> 
>      int i;
>      MPI_Init( &argc, &argv );
>      for(i=0; i< count; i++){
>          array_of_commands[i]="/home/mpitest/spawn";
>          array_of_maxprocs[i]=1;
>          MPI_Info_create(&array_of_info[i]);
>          MPI_Info_set(array_of_info[i],"host",host[i % HLEN]);
>      }
> 
>      MPI_Comm_get_parent( &parentcomm );
>      if (parentcomm == MPI_COMM_NULL) {
>          MPI_Comm_spawn_multiple( count, array_of_commands, MPI_ARGVS_NULL /*array_of_argv*/,
>                  array_of_maxprocs, array_of_info, root, MPI_COMM_WORLD, &intercomm, errcodes );
>          printf("I'm the parent.\n");
>      } else {
>          gethostname(name, sizeof(name));
>          printf("I'm the spawned at %s.\n",name);
>      }   
>      fflush(stdout);
>      MPI_Finalize();
>      return 0;
>  }   
> 
> 
> 
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