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Subject: Re: [OMPI users] MPI debugger
From: Ashley Pittman (ashley_at_[hidden])
Date: 2010-01-15 04:07:42


On 11 Jan 2010, at 06:20, Jed Brown wrote:

> On Sun, 10 Jan 2010 19:29:18 +0000, Ashley Pittman <ashley_at_[hidden]> wrote:
>> It'll show you parallel stack traces but won't let you single step for
>> example.
>
> Two lightweight options if you want stepping, breakpoints, watchpoints,
> etc.
>
> * Use serial debuggers on some interesting processes, for example with
>
> mpiexec -n 1 xterm -e gdb --args ./trouble args : -n 2 ./trouble args : -n 1 xterm -e gdb --args ./trouble args
>
> to put an xterm on rank 0 and 3 of a four process job (there are lots
> of other ways to get here).

You can also achieve something similar with padb by starting the job normally and then using padb to launch xterms in a similar manner although it's been pointed out to me that this only works with one process per node right now.

> * MPICH2 has a poor-man's parallel debugger, mpiexec.mpd -gdb allows you
> to send the same gdb commands to each process and collate the output.

True, I'd forgotten about that, the MPICH2 people are moving away from mpd though so I don't know how much longer that will be an option.

Ashley,