[petsc-dev] adding comm argument to PetscError() and friends

[Matthew Knepley]

On Thu, May 6, 2010 at 10:16 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   I'd like to add a MPI_Comm as the first argument to PetscError() and
> friends.
>
>   In this way, if the same error is known over all the communicator ranks
> it can print just one nice error message and stack instead of spewing out
> many of the same messages all over the place.
>
>   Does anyone object to this?
>

I am just worried that it will introduce deadlocks. If an error occurs on
only one process
and not another (like a NaN), but we use the entire communicator, we can get
deadlock
on the error message which will be very confusing. Is there a nice MPI way
of checking
whether everyone is present, and if not then just use the current method?

   Matt


>   It does mean for each SETERRQXXX() we call we need to select the correct
> comm that is passed in. I will do all that, worst case just use
> MPI_COMM_SELF for some and get the same effect as today.
>
>   Barry
>
-- 
What most experimenters take for granted before they begin their experiments
is infinitely more interesting than any results to which their experiments
lead.
-- Norbert Wiener
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