[mpich-discuss] MPI I/O SLOW- possible conflicting with communication....code stuck for ever during IO

[Rob Latham]

On Sun, Mar 14, 2010 at 02:56:53PM -0400, hossam wrote:
> Now, to make things clearer: When i use ROMIO (MPI IO) it got stuck during
> opining the file (MPI_FILE_OPEN).
> 
> However, i tried regular open(....) at the root processor and then reducing
> the data to the root processor and write there. The code got stuck at the
> MPI_REDUCE call.

You seem to be having problems with the collective routines. It sounds
like one or more of your processors are perhaps off doing something
else while one or more try to open the file.  

If you stick a few print statements in your code and maybe an
MPI_BARRIER, I suspect you'll be able to track down which process or
processes are still in the computation phase.

==rob

-- 
Rob Latham
Mathematics and Computer Science Division
Argonne National Lab, IL USA