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Re: [ptp-user] Now, here's a bug!
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Someone already discovered it: https://bugs.eclipse.org/403397. Sorry, no spotters fee :-).
Cheers,
Greg
On Jun 28, 2013, at 10:29 AM, Dr. David E Hudak <dhudak@xxxxxxx> wrote:
> Hi PTP community,
>
> I found a bug in the eclipse-supplied MPI C example that calculates Pi.
>
> The broadcast on line 93:
> MPI_Bcast(message, strlen(message)+1, MPI_CHAR, dest, MPI_COMM_WORLD);
> ..fails because rank 0's message buffer is "Hi, how are you?" and ranks 1..num_procs-1 message buffer is "Greetings from process 1", "Greetings from process 2", and so on. This leads to calling the MPI_Bcast with different buffer lengths which causes a fault on my cluster.
>
> I recommend it be changed to match the fortran example where everyone uses the max length of the buffer for the broadcast, like so:
> MPI_Bcast(message, 100, MPI_CHAR, dest, MPI_COMM_WORLD);
>
> I tested this change on my cluster and it works.
>
> I would like a refund for the 30 minutes of my life this bug has taken from me. Put it on my tab :-)
>
> Thanks,
> Dave
> ---
> David E. Hudak, Ph.D. dhudak@xxxxxxx
> Senior Research Scientist
> Ohio Supercomputer Center
> http://www.osc.edu/~dhudak
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