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Subject: Re: [OMPI users] Question on MPI_Ssend
From: Jeff Squyres (jsquyres) (jsquyres_at_[hidden])
Date: 2011-09-14 07:09:36


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.devendra_at_[hidden]> 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 <jsquyres_at_[hidden]>
> To: devendra rai <rai.devendra_at_[hidden]>; Open MPI Users <users_at_[hidden]>
> 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
> jsquyres_at_[hidden]
> For corporate legal information go to:
> http://www.cisco.com/web/about/doing_business/legal/cri/
>
>
>