[mpich-discuss] uninitialized MPI_Status object

[Jeff Hammond]

I created a ticket for this:
https://trac.mpich.org/projects/mpich/ticket/2332.

Jeff

On Mon, Mar 28, 2016 at 10:26 AM, Wei-keng Liao <
wkliao at eecs.northwestern.edu> wrote:

> My test program can be compiled with command "mpicc get_count.c -o
> get_count"
> and run "mpiexec -n 4 get_count". For correct (expected) result, nothing
> will be printed on stdout. Otherwise, error messages will be printed.
>
> My point is MPI_Get_count does not report correct result because
> MPI collective I/O call fails to initialize the MPI_Status object.
>
> I found that OpenMPI and earlier version of MPICH (2-1.2.1) can run
> this test code correctly.
>
> The test failed when I ran MPICH 3.1.4 and the current from GIT repo.
>
> Wei-keng
>
> On Mar 26, 2016, at 3:21 PM, יוסף אלון wrote:
>
> > בס"ד
> >
> > becuse all the command confusion.
> > which command should i put to run the above code?
> >
> > 2016-03-26 3:31 GMT+03:00 Wei-keng Liao <wkliao at eecs.northwestern.edu>:
> >
> > I notice an uninitialized MPI_Status object can make MPI_Get_count
> return a wrong result,
> > when the data amount in the MPI operation is zero (although I only
> checked MPI-IO).
> > Attached is a test program that uses MPI collective read where only root
> process has
> > non-zero length data to read. The expected result from MPI_Get_count is
> 0 for all
> > non-root process. To mimic an uninitialized MPI_Status object, I call
> memset to make
> > the object non-zero.
> >
> > Here is the code fragment.
> >
> >     if (rank == 0) len = 10;
> >     else len = 0;
> >
> >     MPI_File_read_all(fh, buf, len, MPI_BYTE, &status);
> >
> >     MPI_Get_count(&status, MPI_BYTE, &get_size);
> >
> > For process rank > 0, get_size may not be 0.
> >
> >
> > Wei-keng
> >
> >
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> >
> >
> > --
> > בברכה, יוסף אלון
> > 050-4916740
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-- 
Jeff Hammond
jeff.science at gmail.com
http://jeffhammond.github.io/
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