[mpich-discuss] Error while using MPI platform with CPP program

[Junchao Zhang]

Antonie is right. You only allocated memory for b on rank 0.  To receive b
on other ranks, you need to allocate memory on them as well.

--Junchao Zhang

On Wed, May 20, 2015 at 5:37 AM, Antoine Rougier <rougier at par.tuwien.ac.at>
wrote:

> Hello,
>
> I think your issue comes from b.vect=NULL (according to the used
> constructor) which is not a checked value in T Vector<T>::get(int i). By
> the way Ncol is no initialized before using it in MPI_Bcast.
>
> best regards,
>
> Antoine Rougier
>
>
> On 05/20/2015 11:55 AM, Umesh Shisode wrote:
> > Hello Junchao,
> >
> > I initialize vector b, but even then it is not working for broadcasting.
> It
> > gives same error. As the vector class is user defined and also I use
> > dynamic memory allocation. This may be the reason for failing. If you
> know
> > about it then please tell.
> > I am here attaching the zip file which contains only the vector class and
> > main file as well as error I am facing. Please have a look at it. Thanks
> > for your time. I am waiting for your reply.
> >
> >
> > Regards,
> >
> > Umesh Sharad Shisode,
> > M.Tech in Modeling and Simulation(2013-15),
> > Centre for Modeling and Simulation,
> > University of Pune.
> >
> > On Tue, May 19, 2015 at 10:57 PM, Junchao Zhang <jczhang at mcs.anl.gov>
> wrote:
> >
> >> Your code "MPI_Bcast(&b(0), b.get_row(), MPI_DOUBLE, 1, MPI_COMM_WORLD)"
> >>  is OK.  You can find manual of MPI_Bcast at
> >> http://mpi.deino.net/mpi_functions/MPI_Bcast.html
> >> Don't forget to initialize the vector b, in other words, allocate memory
> >> for it, on ALL ranks.
> >>
> >>
> >> --Junchao Zhang
> >>
> >> On Tue, May 19, 2015 at 9:27 AM, Umesh Shisode <ushisode1 at gmail.com>
> >> wrote:
> >>
> >>> Hi Junchao,
> >>>
> >>> I sort out the problem for MPI_Send() and MPI_Recv(), as I requested in
> >>> last mail. Now I have one more difficulty which is how can I broadcast
> >>> class object using MPI_Bcast() function. In my case, class is Vector
> (you
> >>> can check it at vect_fun.h header file). I want to broadcast it to all
> >>> processes. I have used dynamic memory allocation in the code. Please
> help
> >>> me to solved the issue. I am waiting for your reply. Thanks.
> >>>
> >>>
> >>> Regards,
> >>>
> >>> Umesh Sharad Shisode,
> >>> M.Tech in Modeling and Simulation(2013-15),
> >>> Centre for Modeling and Simulation,
> >>> University of Pune.
> >>>
> >>> On Tue, May 19, 2015 at 7:51 AM, Umesh Shisode <ushisode1 at gmail.com>
> >>> wrote:
> >>>
> >>>> Sorry Junchao,
> >>>>
> >>>> Thanks for your reply. But my problem is with MPICH only. My question
> is
> >>>> how to send part of class object (in my case matrix object) from one
> >>>> process to another process using MPI_Send and receive using MPI_Recv
> >>>> functions. I tried a lot of way but couldn't do it. I hope you will
> help
> >>>> me. Thanks in advance. I have write a function to get the pointer
> address
> >>>> for first parameter of MPI_Send() function. Waiting for your reply.
> >>>>
> >>>> Regards,
> >>>>
> >>>> Umesh Sharad Shisode,
> >>>> M.Tech in Modeling and Simulation(2013-15),
> >>>> Centre for Modeling and Simulation,
> >>>> University of Pune.
> >>>>
> >>>> On Mon, May 18, 2015 at 7:31 PM, Junchao Zhang <jczhang at mcs.anl.gov>
> >>>> wrote:
> >>>>
> >>>>> Could not reproduce it with the latest MPICH.  If the problem is not
> >>>>> specific to MPICH, you'd better move your question to other forums
> like
> >>>>> stackoverflow.
> >>>>>
> >>>>> $mpirun -n 2 ./test
> >>>>> Matrix A :
> >>>>>
> >>>>> 1 2 3 4
> >>>>> 1 2 3 4
> >>>>> 1 2 3 4
> >>>>> 1 2 3 4
> >>>>>
> >>>>> Vector b before broadcast:
> >>>>>  1.000000,  2.000000,  3.000000,  4.000000
> >>>>> Matrix A column : 4
> >>>>> after sending:  lLim = 2 uLim = 4  for rank : 1
> >>>>> count = 8
> >>>>>
> >>>>> Matrix A column : 0for rank = 1
> >>>>> after receive:  lLim = 2 uLim = 4  for rank : 1
> >>>>> Ncol after broadcasting = 4
> >>>>>
> >>>>>
> >>>>> --Junchao Zhang
> >>>>>
> >>>>> On Mon, May 18, 2015 at 6:33 AM, Umesh Shisode <ushisode1 at gmail.com>
> >>>>> wrote:
> >>>>>
> >>>>>> Hello Sir / Madam,
> >>>>>>
> >>>>>> This is Umesh Sharad Shisode, pursuing Masters in Modeling and
> >>>>>> Simulation, at Centre for Modeling and Simulation, Pune University.
> I am in
> >>>>>> the final stage of my course. My Masters Thesis title is :
> >>>>>>
> >>>>>>     Development of Conjugate Gradient solver in OpenFOAM / CPP using
> >>>>>> MPI
> >>>>>>
> >>>>>> I am now doing MPI part of my project and facing some problems with
> >>>>>> MPI functions syntax. I am trying to use CPP class object with MPI
> >>>>>> functions but it is giving some error. Which I don't understand.
> >>>>>>
> >>>>>> Operating system         : LINUX
> >>>>>> Programming Language : CPP
> >>>>>>
> >>>>>> Commands I am using are :
> >>>>>>
> >>>>>>        > mpic++ main.cpp -o result
> >>>>>>        > mpirun -np 2 result
> >>>>>>
> >>>>>> Please help me to sort out this issue . I am attaching herewith zip
> >>>>>> file containing the code which I want to parallelize with the png
> file
> >>>>>> containing error. Waiting for your reply. Thanks in advance.
> >>>>>>
> >>>>>> Regards,
> >>>>>>
> >>>>>> Umesh Sharad Shisode,
> >>>>>> M.Tech in Modeling and Simulation(2013-15),
> >>>>>> Centre for Modeling and Simulation,
> >>>>>> University of Pune.
> >>>>>>
> >>>>>>
> >>>>>> _______________________________________________
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> >>>>>
> >>>>>
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