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From: Michael Epitropakis (mikeagn_at_[hidden])
Date: 2007-03-12 12:25:48


Dear ompi users,

I am using OpenMPI in order to parallelize an evolutionary algorithm.
During the execution of the algorithm I have to send many same messages to
some nodes. So, in order to generate and use these messages i use MPI_Pack
and MPI_Unpack Each message has the following structure:

{int, int, int[size], double[size2], double}

In the beginning of the Algorithm everything is going well... but suddenly
something is going wrong and i get the following messages::

[compute-0-1.local:32461] *** An error occurred in MPI_Unpack
[compute-0-1.local:32461] *** on communicator MPI_COMM_WORLD
[compute-0-1.local:32461] *** MPI_ERR_TRUNCATE: message truncated
[compute-0-1.local:32461] *** MPI_ERRORS_ARE_FATAL (goodbye)

With a lot of debugging I found out that the first two integers, let me
call them x, y, were not the values that i was expecting (the values that
i have packed!!!). They were very strange: either big positive integers or
big negative integers. I checked the buffer that I am using for these
messages and it is much bigger than the required message storage. I can;t
think of something else that could probably caused that problem

Can you please help me with this?? What could have probably caused this
problem?

I am using OpenMPI version: Open MPI: 1.1 Open MPI SVN revision: r10477

Thank you in advance
Michael.