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

Wed May 20 12:59:51 CDT 2015

First, as far as I understand, the broadcast should not be between
blocking send on a process and blocking recv on the others. You have to
change your code if you want to keep using blocking communication.

Then, by running (with the previous modifications), I have got:
Fatal error in MPI_Recv: Invalid buffer pointer, error stack:
MPI_Recv(187): MPI_Recv(buf=(nil), count=8, MPI_DOUBLE, src=0, tag=3,
MPI_COMM_WORLD, status=0x7fffbc4e02d0) failed
MPI_Recv(126): Null buffer pointer

It is probably an issue on your side, such as bad index.

Antoine Rougier

On 05/20/2015 05:17 PM, Umesh Shisode wrote:
> Hello Antoine Rougier,
> 
> Thanks for your reply. Now I have code which can broadcast vector as well
> as Matrix object (Attached here). But it is giving error when I tried to
> send and receive part of matrix object it is giving me error. Thanks again
> for your time. Please help me out. As it is not giving me correct answer. I
> am waiting for your reply.
> Sorry for your inconvenience.
> 
> I have attached here new code. It compiles when I want to broadcast. But
> giving error for send and receive. I also attached error in png file.
> 
> Regards,
> 
> Umesh Sharad Shisode,
> M.Tech in Modeling and Simulation(2013-15),
> Centre for Modeling and Simulation,
> University of Pune.
> 
> On Wed, May 20, 2015 at 4:07 PM, 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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