[mpich-discuss] Running MPI jobs without mpiexec

[Jayesh Krishna]

Hi,
 I am not sure what you mean by "running" a dll (Are you referring to using "rundll" etc ? ). 
 What is the advantage that you get by running dlls instead of executables ?

Regards,
Jayesh

----- Original Message -----
From: "Amar K. Patel" <PATEL_AMAR_K at cat.com>
To: jayesh at mcs.anl.gov
Cc: mpich-discuss at mcs.anl.gov
Sent: Monday, August 15, 2011 10:58:37 AM
Subject: Re: [mpich-discuss] Running MPI jobs without mpiexec


Hi Jayesh, 

Thanks for suggesting the two options earlier. I have been exploring them since your recommendations and I would appreciate if you could answer these follow-up questions. 

1. I have been looking at MPI_Comm_spawn_multiple and MPI_Comm_spawn under MPI dynamic processes and I have concluded that for either of these options to work, the callee binary should be an exe. Am I correct to conclude this? 

Meaning that if I have the following line in my main code (call it myCode2.exe), 

MPI_Comm_spawn_multiple(NHOST, progs, MPI_ARGVS_NULL, nproc, infos, 0, MPI_COMM_WORLD, &intercomm, MPI_ERRCODES_IGNORE); 

the binary specified under "Progs" argument should be an exe and not a dll or a lib file. Is this correct ? 

Here is a little background on what I am trying to do here. 
I am trying to call a shared library (dll) that needs to be run on multiple processors but I do not want the main calling program to be run on multiple PCs. So basically, I need to run the main program (myCode2.exe) as a singleton process which at run time needs to call a dll (myCode1.dll) and that dll needs to be run on multiple processors. 
I have tried putting in MPI_Comm_spawn_multiple in the main program and tried to call the dll through MPI_Comm_spawn_multiple but I get a runtime error indicating that the program being called by MPI_Comm_spawn_multiple is not an executable. 

2. Your other suggestion was launching mpiexec from the main program (myCode2.exe). Are you suggesting using the system() function in myCode2.exe to launch mpiexec which then launches myCode1? Wont this require myCode1 to be an exe file to be launched with mpiexec command? In my case myCode1 used to be compiled as a standalone exe file before, but we would now wish to compile it as a dll that is loaded as a shared library and called by another larger executable at run time. 

Thanks for your help. 

Amar 




	Jayesh Krishna <jayesh at mcs.anl.gov> 
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08/04/2011 03:28 PM 	
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Hi, 
Two options come to my mind, 

# Take a look at MPI dynamic processes (http://www.mpi-forum.org/docs/mpi21-report/node197.htm#Node197). 
# Launch mpiexec from myCode2. 

Regards, 
Jayesh 
----- Original Message ----- 
From: "Amar K. Patel" <PATEL_AMAR_K at cat.com> 
To: mpich-discuss at mcs.anl.gov 
Sent: Thursday, August 4, 2011 11:35:58 AM 
Subject: [mpich-discuss] Running MPI jobs without mpiexec 



Hello, 

I have MPI program that runs fine when it started with the command mpiexec -n # myCode1.exe. I now need to call myCode1 from another code (say myCode2) in such a way that myCode1 is a dll file which is loaded and called when myCode2 is being executed. myCode2 is started without using mpiexec commad. 

With this new setup I would like to call myCode1.dll and be able to use the MPI features that have been embedded in it such that myCode1.dll can be run on more than one CPU. Is such a thing possible ? If so, then I would appreciate if someone could point me to a documentation or an example that illustrates how to implement the changes needed in myCode1 and/or myCode2. 

Here is an crude version of myCode1 and myCode2 that I am using. 

void myCode1() 
{ 
int rank; 
MPI_Init(x, x); 
MPI_Comm_rank(MPI_COMM_WORLD, &rank); 
...... 
...... 
...... 
...... 
...... 
...... 
...... 
...... 
MPI_Finalize(); 
return; 
} 


int myCode2(int argc, char **argv) 
{ 
myCode1(); 
return 0; 
} 
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