Re: [OMPI users] Help!

[Eugene Loh]

guosong wrote: I am new to open MPI I am not, but I'm not real familiar with thread-safe MPI programming.  Still, I saw no other replies to your question, so I'll make an attempt to answer. MPI does not guarantee thread safety.  E.g., see http://www.mpi-forum.org/docs/mpi-20-html/node162.htm#Node162 and the ensuing pages. To do what you want to do, you need to make sure you have thread safety.  There is a standard MPI interface for doing so.  I'm not good at C++, so here is a C example: #include <stdio.h> #include <mpi.h> int main(int argc, char **argv) {   int provided;   /* start MPI, asking for support for multiple threads */   MPI_Init_thread(&argc,&argv,MPI_THREAD_MULTIPLE,&provided);   /* report what level of support is actually provided */   if ( MPI_THREAD_SINGLE     == provided ) printf(" MPI_THREAD_SINGLE\n");   if ( MPI_THREAD_FUNNELED   == provided ) printf(" MPI_THREAD_FUNNELED\n");   if ( MPI_THREAD_SERIALIZED == provided ) printf(" MPI_THREAD_SERIALIZED\n");   if ( MPI_THREAD_MULTIPLE   == provided ) printf(" MPI_THREAD_MULTIPLE\n");   /* exit */   MPI_Finalize();   return 0; } Run this program.  If the program does not print out "MPI_THREAD_MULTIPLE", you're not getting the level of thread support you require and your program is not guaranteed to run properly.  You have to make sure you're using a thread-safe MPI before you can expect your program to work. The next question is whether Open MPI is thread safe, and I'll leave you with this: http://www.open-mpi.org/faq/?category=supported-systems#thread-support Good luck.  Again, I'm not experienced with thread-safe MPI programming (though I understand the general concepts).