[mpich-discuss] MPI_THREAD_MULTIPLE

[Lubomir Radev]

This works for me too, returning MPI_THREAD_MULTIPLE, but only when started via mpiexec.

However, I need to launch my worker processes programmatically by using MPI_Comm_spawn_multiple(). That's necessitated by the nature of my app - it's actually a library that clients will be linking against. So the client process has to spawn workers and communicate with them, which works just fine from one thread and fails with two. And if I use MPI_Init_thread() from the client/master process (which isn't started by mpiexec), it always returns MPI_THREAD_SINGLE.

Should I try to pack all of my MPI communications in one thread or can you suggest a solution other than mpiexec for multiple threads? Perhaps I could somehow perform the same thread support initialization that mpiexec apparently does internally?

Thanks very much.



________________________________
From: Jayesh Krishna <jayesh at mcs.anl.gov>
To: mpich-discuss at mcs.anl.gov
Cc: Lubomir Radev <lubomirr at yahoo.com>
Sent: Monday, September 21, 2009 9:04:17 AM
Subject: RE: [mpich-discuss] MPI_THREAD_MULTIPLE

 
Hi,
 Are you launching your MPI job using the 
"-channel" option of mpiexec (mpiexec -n 2 -channel nemesis 
thread_multiple_test.exe)? A simple MPI program (see 
below) that queries for the thread level support returns 
MPI_THREAD_MULTIPLE for me.
 
=========== Thread multiple test 
===================
#include<iostream>
#include"mpi.h"
intmain(intargc, char*argv[]){
intprovided;provided = MPI::Init_thread(MPI_THREAD_MULTIPLE);
if(provided == MPI_THREAD_MULTIPLE){
std::cout << "Thread multiple supported"<< 
std::endl;}
else{
std::cout << "Thread multiple NOT supported"<< 
std::endl;}
MPI::Finalize();
}
=========== Thread multiple test 
===================
 
Regards,
Jayesh


________________________________
 From: mpich-discuss-bounces at mcs.anl.gov 
[mailto:mpich-discuss-bounces at mcs.anl.gov] On Behalf Of Lubomir 
Radev
Sent: Sunday, September 20, 2009 7:23 PM
To: mpich-discuss at mcs.anl.gov
Subject: Re: [mpich-discuss] 
MPI_THREAD_MULTIPLE


Yes. I was using 1.0.8p1 originally, but after your suggestion got 1.1.1p1 
and the problem persists.

I could reduce my code to a test case exhibiting the issue, but I need to 
understand why MPI_Init_thread() won't provide me with MPI_THREAD_MULTIPLE 
support and always returns MPI_THREAD_SINGLE regardless of the channel 
configuration. I need to get that working first so my multi-threaded code can 
assume it operates in a correctly initialized environment and can legitimately 
call into MPICH2 simultaneously from more than one thread.

I'm using Boost.MPI wrapper (and Boost.Thread), but that shouldn't 
matter.

Thanks


________________________________
 From: Jayesh Krishna 
<jayesh at mcs.anl.gov>
To: mpich-discuss at mcs.anl.gov
Sent: Friday, September 18, 2009 8:42:38 AM
Subject: Re: [mpich-discuss] 
MPI_THREAD_MULTIPLE


Hi,
 Are you trying the latest stable release, 
1.1.1p1, of MPICH2 (http://www.mcs.anl.gov/research/projects/mpich2/downloads/index.php?s=downloads) 
?
 Can you send us a test program 
?

Regards,
Jayesh

-----Original Message-----
From: 
mpich-discuss-bounces at mcs.anl.gov [mailto:mpich-discuss-bounces at mcs.anl.gov] 
On Behalf Of Lubomir Radev
Sent: Thursday, September 17, 2009 10:08 PM
To: 
mpich-discuss at mcs.anl.gov
Subject: [mpich-discuss] 
MPI_THREAD_MULTIPLE

Hey guys,

I need to call into the thread-safe 
version of MPICH2 so I tried to initialize with MPI_Init_thread() and 
MPI_THREAD_MULTIPLE, but no matter how I configured the channels on my nodes - 
tried both mt and nemesis - that function returns MPI_THREAD_SINGLE as provided 
thread support.

I'm using 1.0.8p1 on Windows if that matters. Installed 
from the provided MSI binary. Perhaps I need to build from sources, configuring 
it with thread support?

Thanks
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