Ah!  Are you using MPI-thread-multiple?

Sent from my phone. No type good. 

On Sep 14, 2011, at 5:28 AM, "devendra rai" <rai.deven...@yahoo.co.uk> wrote:

> Hello MPI Forum, Jeff
> 
> Well, the problem is not with incorrect arguments with MPI_Ssend(...) and/or 
> MPI_Recv(...).  I confirmed this. Also, if there were any obvious programming 
> and logical errors, I would never have any successful run. In fact, I am 
> having some  runs which go through successfully.
> 
> The problem seems to be random, and therefore, I am finding it hard to debug. 
> I am using Open MPI v. 1.4.3, on Linux kernel 2.6.37.6-0.7. 
> 
> I am also using tags, in addition to normal sender node and receiver nodes. I 
> am using integers for tags, and none of the tags are more than 1000. I am 
> also running MPI_Ssends and MPI_Recv within pthreads, and I  believe that it 
> should be okay.
> 
> So, the question is, am I stumbling across a bug, or an incorrect MPI 
> installation?
> 
> Thanks a lot.
> 
> Best
> 
> Devendra
> 
> From: Jeff Squyres <jsquy...@cisco.com>
> To: devendra rai <rai.deven...@yahoo.co.uk>; Open MPI Users 
> <us...@open-mpi.org>
> Sent: Tuesday, 13 September 2011, 16:13
> Subject: Re: [OMPI users] Question on MPI_Ssend
> 
> On Sep 13, 2011, at 8:41 AM, devendra rai wrote:
> 
> > Also, I read the definition of MPI_Ssend(...) that you sent, but then it 
> > does not explain why both MPI_Ssend(...) and MPI_Recv(...) are blocked 
> > seemingly forever. 
> 
> Oh, they're blocked *forever*!  Sorry; I didn't get that from your prior 
> description -- I thought you just wanted non-blocking instead of blocking.
> 
> > I notice that such a block happens when MPI_Recv(...) is posted before 
> > MPI_Ssend(...).
> 
> It doesn't matter if the receive is posted before the send or the other way 
> around.
> 
> When blocking sends/receives block forever, it usually means that there's a 
> mismatch in the communicator, tag, or src/dest arguments between the two.
> 
> -- 
> Jeff Squyres
> jsquy...@cisco.com
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
> 
> 
> 

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