[mpich-discuss] uninitialized MPI_Status object

[יוסף אלון]

i don't know why, but the first command works and the second command isnt.
i have the following error:
[image: תמונה מוטבעת 1]

what this means?

2016-03-28 21:15 GMT+03:00 Jeff Hammond <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> 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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-- 
בברכה, יוסף אלון
050-4916740
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