[MPICH] MPI hint cb_nodes used in both open and setview

[Rob Ross]

Hi Wei-keng,

Thanks for pointing out this bug. So what do you think that it should  
do? Ignore the subsequent values for cb_nodes, or recalculate  
aggregators?

Rob

On Feb 8, 2008, at 11:28 PM, Wei-keng Liao wrote:

>
> I found that when a program uses the ROMIO hint cb_nodes in an MPI  
> info
> object and the info object is used in both MPI_File_open and
> MPI_File_set_view, the latter will overwrite the value of
> fd->hints->cb_nodes that first was set in MPI_File_open.
>
> I think MPI does not say one cannot use the same info in both open and
> set_view.
>
> For example, a program allocates 10 MPI processes on a cluster with 2
> processes per compute node. If the user sets cb_nodes hint to 7,
> MPI_File_open will "intelligently" set fd->hints->cb_nodes to 5 and
> allocate space for fd->hints->ranklist[] (of size 5), but later
> MPI_File_set_view will change fd->hints->cb_nodes back to 7. So, when
> fd->hints->ranklist[] is referred in ADIOI_Calc_aggregator(), it may  
> refer
> fd->hints->ranklist[5,6], which is out of array boundary.
>
> I have a simple program that generates coredump because of this.
>
> Wei-keng
>