Classification: UNCLASSIFIED Caveats: NONE Okay, I think I may get what's going on. I think you're calling one mpi capable program from within another mpi program. What you have to do is assume that the program that is being called already had MPI_Init called and that MPI_Finalize will be called after the program returns.
Example (pseudocode for brevity):
int main()
{
MPI_Init();
int x;
int p2result = Program2(x, comm);
MPI_Bcast(p2result, comm);
MPI_Finalize();
}
int Program2(int x, MPI_Comm comm)
{
int returnval;
MPI_AllReduce(&returnval, x, comm);
return returnval;
}
If the second program were to be:
int Program2(int x, MPI_Comm comm)
{
MPI_Init();
int returnval;
MPI_AllReduce(&returnval, x, comm);
return returnval;
MPI_Finalize()
}
The program would return to serial when MPI_Finalize is first called,
potentially throwing several errors.
-Andrew Burns
-----Original Message-----
From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Muhammad Ashfaqur
Rahman
Sent: Wednesday, February 04, 2015 3:42 PM
To: Open MPI Users
Subject: Re: [OMPI users] prob in running two mpi merged program (UNCLASSIFIED)
Dear Andrew Burns,
Thank you for your ideas. Your guess is partly correct, I am trying to merge
two sets of programs into one executable and then run
in mpi.
As per your suggestion, I have omitted the MPI_Finalize from of one set. And
also commented the MPI_Barrier in some parts.
But still it is serial.
For your idea: attached here Makefile.
Regards
Ashfaq
On Tue, Feb 3, 2015 at 6:26 PM, Burns, Andrew J CTR (US)
<andrew.j.burns35....@mail.mil> wrote:
Classification: UNCLASSIFIED
Caveats: NONE
If I could venture a guess, it sounds like you are trying to merge two
separate programs into one executable and run them in
parallel
via MPI.
The problem sounds like an issue where your program starts in parallel
but then changes back to serial while the program is
still
executing.
I can't be entirely sure without looking at the code itself.
One guess is that MPI_Finalize is in the wrong location. Finalize
should be called to end the parallel section and move the
program
back to serial. Typically this means that Finalize will be very close
to the last line of the program.
It may also be possible that with the way your program is structured,
the effect is effectively serial since only one core
is
processing at any given moment. This may be due to extensive use of
barrier or similar functions.
Andrew Burns
Lockheed Martin
Software Engineer
410-306-0409
ARL DSRC
andrew.j.bur...@us.army.mil
andrew.j.burns35....@mail.mil
-----Original Message-----
From: users [mailto:users-boun...@open-mpi.org] On Behalf Of Ralph
Castain
Sent: Tuesday, February 03, 2015 9:05 AM
To: Open MPI Users
Subject: Re: [OMPI users] prob in running two mpi merged program
I'm afraid I don't quite understand what you are saying, so let's see
if I can clarify. You have two fortran MPI programs.
You start
one using "mpiexec". You then start the other one as a singleton -
i.e., you just run "myapp" without using mpiexec. The two
apps are
attempting to execute an MPI_Connect/accept so they can "join".
Is that correct? You mention MPICH in your statement about one of the
procs - are you using MPICH or Open MPI? If the
latter, which
version are you using?
Ralph
On Mon, Feb 2, 2015 at 11:35 PM, Muhammad Ashfaqur Rahman
<ashfaq...@gmail.com> wrote:
Dear All,
Take my greetings. I am new in mpi usage. I have problems in
parallel run, when two fortran mpi programs are merged
to one
executable. If these two are separate, then they are running parallel.
One program has used spmd and another one has used mpich
header directly.
Other issue is that while trying to run the above mentioned
merged program in mpi, it's first started with separate
parallel
instances of same step and then after some steps it becomes serial.
Please help me in this regards
Ashfaq
Ph.D Student
Dept. of Meteorology
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Classification: UNCLASSIFIED
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