[mpich-discuss] Failed to allocate memory for an unexpected message

[Luiz Carlos da Costa Junior]

Hi Pavan and Antonio,

I implemented the scheme you suggested and it was much easier than I
thought. Very nice, thanks for your help.

However, I noticed that the execution times were much higher than the cases
in which the failure didn't occur.
Is there any reason, apart from some implementation mistake, to explain
this behavior?

I don't know if it would help, but I am sending below part of the receiver
process Fortran code.

Thanks in advance.

Best regards,
Luiz

c-----------------------------------------------------------------------
      subroutine my_receiver
c     ------------------------------------------------------------------
      (...)

c     Local
c     -----
      integer*4 m_stat(MPI_STATUS_SIZE)

      integer*4 m_request(zrecv)        ! request identifier
for asynchronous receives
      character card(zrecv)*(zbuf)      ! buffer for receiving messages

c     Pre-post RECVs
c     --------------
      do irecv = 1, zrecv
        call MPI_IRECV(card(irecv), zbuf, MPI_CHARACTER,
     .                 MPI_ANY_SOURCE, MPI_ANY_TAG, M_COMM_SDDP,
     .                 m_request(irecv), m_ierr )
      end do !irecv

      do while( keep_receiving )

c       Wait for any of the pre-posted requests to arrive
c       -------------------------------------------------
        call MPI_WAITANY(zrecv, m_request, irecv, m_stat, m_ierr)

c       Process message: disk IO
c       ---------------
        <DO SOMETHING>
        if( SOMETHING_ELSE ) then
          keep_receiving = .false.
        end if

c       Re-post RECV
c       ------------
        call MPI_IRECV(card(irecv), zbuf, MPI_CHARACTER,
     .                 MPI_ANY_SOURCE, MPI_ANY_TAG, M_COMM_SDDP,
     .                 m_request(irecv), m_ierr)

      end do

c     Cancel unused RECVs
c     -------------------
      do irecv = 1, zrecv
        call MPI_CANCEL( m_request(irecv), m_ierr )
      end do !irecv

      (...)

      return
      end




On 1 November 2013 22:14, Luiz Carlos da Costa Junior <lcjunior at ufrj.br>wrote:

> Thanks
>
>
> On 1 November 2013 22:00, Pavan Balaji <balaji at mcs.anl.gov> wrote:
>
>>
>> On Nov 1, 2013, at 4:30 PM, Luiz Carlos da Costa Junior <lcjunior at ufrj.br>
>> wrote:
>> > I understand that I will have to have N buffers, one for each posted
>> MPI_Irecv. I will also have to TEST (using MPI_PROBE or MPI_WAITANY) until
>> a message comes. The result of this test will identify which one of the
>> posted MPI_Irecv has actually received the message and then process the
>> right buffer. Is this correct?
>>
>> Correct.
>>
>> > Should I have to change anything at the sender's processes?
>>
>> Likely not.  But you need to think through your algorithm to confirm that.
>>
>> > At the end, my receiver process receives a message identifying that it
>> should exit this routine. What should I do with the already posted
>> MPI_Irecv's? Can I cancel them?
>>
>> Yes, you can with MPI_CANCEL.
>>
>>   —- Pavan
>>
>> --
>> Pavan Balaji
>> http://www.mcs.anl.gov/~balaji
>> _______________________________________________
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>
>
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