[petsc-users] Debugger question

[Matthew Knepley]

On Mon, Apr 2, 2012 at 8:57 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
> On Apr 2, 2012, at 8:10 PM, Tabrez Ali wrote:
>
> > Hello
> >
> > I am trying to debug a program using the switch
> '-on_error_attach_debugger' but  the vendor/sysadmin built PETSc 3.2.00 is
> unable to start the debugger in xterm (see text below). But xterm is
> installed. What am I doing wrong?
> >
> > Btw the segfault happens during a call to MatMult but only with
> vendor/sysadmin supplied PETSc 3.2 with PGI and Intel compilers only and
> _not_ with CRAY or GNU compilers.
>
>    My advice, blow off "the vendor/sysadmin supplied PETSc 3.2" and just
> built it yourself so you can get real work done instead of trying to debug
> their mess.   I promise the vendor one is not like a billion times faster
> or anything.


If you want to justify this to anyone (like a funder), just run both on ex5
for a large size and look at the flops on MatMult. That
is probably your dominant cost (or your PC).

   Matt


>
>   Barry
>
>
>
> >
> > I also dont get the segfault if I build PETSc 3.2-p7 myself with
> PGI/Intel compilers.
> >
> > Any ideas on how to diagnose the problem? Unfortunately I cannot seem to
> run valgrind on this particular machine.
> >
> > Thanks in advance.
> >
> > Tabrez
> >
> > ---
> >
> > stali at krakenpf1:~/meshes> which xterm
> > /usr/bin/xterm
> > stali at krakenpf1:~/meshes> aprun -n 1 ./defmod -f
> 2d_point_load_dyn_abc.inp -on_error_attach_debugger
> > ...
> > ...
> > ...
> > [0]PETSC ERROR:
> ------------------------------------------------------------------------
> > [0]PETSC ERROR: Caught signal number 11 SEGV: Segmentation Violation,
> probably memory access out of range
> > [0]PETSC ERROR: Try option -start_in_debugger or
> -on_error_attach_debugger
> > [0]PETSC ERROR: or see
> http://www.mcs.anl.gov/petsc/petsc-as/documentation/faq.html#valgrind[0]PETSCERROR: or try
> http://valgrind.org on GNU/linux and Apple Mac OS X to find memory
> corruption errors
> > [0]PETSC ERROR: configure using --with-debugging=yes, recompile, link,
> and run
> > [0]PETSC ERROR: to get more information on the crash.
> > [0]PETSC ERROR: User provided function() line 0 in unknown directory
> unknown file
> > [0]PETSC ERROR: PETSC: Attaching gdb to ./defmod of pid 32384 on display
> localhost:20.0 on machine nid10649
> > Unable to start debugger in xterm: No such file or directory
> > aborting job:
> > application called MPI_Abort(MPI_COMM_WORLD, 0) - process 0
> > _pmii_daemon(SIGCHLD): [NID 10649] [c23-3c0s6n1] [Mon Apr  2 13:06:48
> 2012] PE 0 exit signal Aborted
> > Application 133198 exit codes: 134
> > Application 133198 resources: utime ~1s, stime ~0s
>
>


-- 
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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