[mpich-discuss] uninitialized MPI_Status object

[Kenneth Raffenetti]

Try "mpiexec -n 1 ./get_count".

On 03/30/2016 08:46 AM, יוסף אלון wrote:
> i don't know why, but the first command works and the second command isnt.
> i have the following error:
> תמונה מוטבעת 1
>
> what this means?
>
> 2016-03-28 21:15 GMT+03:00 Jeff Hammond <jeff.science at gmail.com
> <mailto:jeff.science at gmail.com>>:
>
>     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 <mailto: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
>         <mailto: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 <mailto:jeff.science at gmail.com>
>     http://jeffhammond.github.io/
>
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> --
> בברכה, יוסף אלון
> 050-4916740
>
>
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