Re: [Pympi-users] PyMPI Doubt

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Sorry for the delay in replying. Pat Miller is better qualified to
answer this question, but I will try to outline the answer. 
 
pympi is itself a special version of the python interpreter that is mpi
aware. Most users are specifically using pympi, because it allows them
to AVOID having to write parallel programs in a low level language like
C. 
 
pympi is mpi aware, because it initialises the MPI processes at
startup. You access them through the loading of the mpi module with
this statement: 
&gt;&gt;&gt; import mpi 
 
There is an example of the other approach, where the mpi calls are made
in a compiled module here: 
 
<a class="moz-txt-link-freetext" href="http://pympi.sourceforge.net/examples.html">http://pympi.sourceforge.net/examples.html</a> 
 
See the simple extension example. This is actually a python extension
that also includes mpi calls using the MPI C api directly without going
through python, for instance it uses the C api to get it's own rank: 
 
<pre>MPI_Comm_rank(MPI_COMM_WORLD,&amp;rank);

</pre>
I have not used the C api myself from pympi, for the reasons I stated
at the beginning:<br>
<br>
regards<br>
<br>
Julian Cook<br>
<a class="moz-txt-link-abbreviated" href="mailto:cha...@gm...">cha...@gm...</a> wrote:
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  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">I read about the PyMPI
tool and I found it to be very
interesting. I was wondering if I could use this tool for my purpose.
It would
be great if you could suggest a solution after I describe the problem
below.<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">I am dealing with
Software called E-cell. The structure of
the software goes like this,<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Core Layer
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;------------------------------------------------</span></font><font   face="Wingdings"><span style="font-family: Wingdings;">&agrave;</span></font><font   face="Arial"><span style="font-family: Arial;">&nbsp;&nbsp;&nbsp; C++<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Interface Layer&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;
------------------------------------------------</span></font><font   face="Wingdings"><span style="font-family: Wingdings;">&agrave;</span></font><font   face="Arial"><span style="font-family: Arial;">&nbsp;&nbsp;&nbsp; Python<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Uses Boost library.<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">When the software is
installed (using make command), all c++
files are compiled into a .so.2 file. Then Python code references this
.so.2
file to make use of the functions in C++. The main exists in Python and
not in
C++. We want to parallelize this software. So we changed the compiler
from gcc
to mpicc. Since Python is the interface layer we are still not able to
initialize MPI and use it in the C++ program. Will installing PyMPI
solve our
problem? All the mpi coding that we are going to perform will be done
in a
&nbsp;C++ file. But ultimately python will reference them. Python acts as a
master and uses the functions in C++. <o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Mpicc can compile c++
programs.<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Can PyMPI also compile
C++ programs?<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Can you please let us
know if installing PyMPI can solve our
problem?<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Thanks,<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;">Chandu<o:p></o:p></span></font></p>
  <p class="MsoNormal"><font face="Arial" size="2"><span   style="font-size: 10pt; font-family: Arial;"><o:p>&nbsp;</o:p></span></font></p>
  </div>
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