Thomas,
thanks for the report,
at first glance, libnbc (the default module that implements non blocking
collective) does not retain/release datatypes, that is why you ran into
this kind of trouble.
I quickly checked the code, and it seems this kind of mechanism is also
missing for MPI_Isend/MPI_Irecv ...
I will investigate this further
Cheers,
Gilles
On Wednesday, January 13, 2016, Thomas Ponweiser <
thomas.ponwei...@risc-software.at
<javascript:_e(%7B%7D,'cvml','thomas.ponwei...@risc-software.at');>> wrote:
> Dear friends of Open MPI,
>
> I am currently facing a problem in connection with MPI_Ibcast and
> MPI_Type_free. I've been able to isolate the problem in a minimalistic test
> program which I attached.
>
> Maybe some of you can tell me what I am doing wrong or confirm that this
> might be a bug in Open MPI (I am using version 1.10.1).
>
> Here is what I am doing:
> 1) I have two struct types, foo_type and bar_type, as follows:
>
> typedef struct
> {
> int v[6];
> long l;
> } foo_type;
>
> typedef struct
> {
> int v[3];
> foo_type foo;
> } bar_type;
>
> 2) I am creating corresponding MPI types (foo_mpitype and bar_mpitype)
> with MPI_Type_create_struct.
>
> 3) I am freeing foo_mpitype.
>
> 4) I am broadcasting a variable of type bar_type with MPI_Ibcast (using
> count = 1 and datatype = bar_mpitype).
>
> 5) I am freeing bar_mpitype.
>
> 6) I am waiting for the completion of step 4) with MPI_Wait.
>
> In step 6) I get a segmentation fault within MPI_Wait, but only if the MPI
> job is larger than 4 processes.
>
> Testing with MPICH 3.2, the program seems to work just fine.
>
> I found out that swapping the steps 5) and 6) helps. But I think this
> should not make any difference, according to the description of
> MPI_Type_free at
> http://www.mpi-forum.org/docs/mpi-1.1/mpi-11-html/node58.html: "Any
> communication that is currently using this datatype will complete
> normally." And: " Freeing a datatype does not affect any other datatype
> that was built from the freed datatype."
>
> (In fact, doing the same thing, that is MPI_IBcast followed by
> MPI_Type_free followed by MPI_Wait, with foo_type and foo_mpitype seems to
> work fine).
>
> Thanks in advance for your help,
>
> kind regards,
> Thomas
>
>
