[petsc-users] KSPSolve() passes in the dbg mode, but failed in opt mode

[Matthew Knepley]

On Mon, Jul 25, 2016 at 2:39 PM, Xujun Zhao <xzhao99 at gmail.com> wrote:

> Another interesting phenomenon is that it works for an iterative solver,
> but only failed for direct solvers(both superLU_dist and mumps). If
> something is not initialized correctly, why doesn't the iterative solver,
> for example, GMRES, throw any errors?
>

It would of course depend on what you have not initialized, and what value
was sitting in that place to begin with.
Use valgrind to clear all this up.

   Matt


> On Mon, Jul 25, 2016 at 11:50 AM, Matthew Knepley <knepley at gmail.com>
> wrote:
>
>> On Mon, Jul 25, 2016 at 9:17 AM, Xujun Zhao <xzhao99 at gmail.com> wrote:
>>
>>> Hi all,
>>>
>>> I am trying to solve my problem with a direct solver superLU_dist.
>>> But the KSPSolve failed in the "opt" mode. I shifted to the "dbg"
>>> version and wanted to see what error info I can get from the PETSc.
>>> Surprisingly, it passed the solve and didn't output any errors in the "dbg"
>>> version. Does anyone have the similar experience? and what type of
>>> potential bugs it may have?
>>>
>>
>> Debugging mode initializes all variables, but as Hong says, valgrind will
>> warn you of uninitialized variables.
>>
>>    Matt
>>
>>
>>>
>>> --->test in StokesSolver::solve(): Start the KSP solve...
>>>
>>> [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/documentation/faq.html#valgrind
>>>
>>> [0]PETSC ERROR: 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: --------------------- Error Message
>>> --------------------------------------------------------------
>>>
>>> [0]PETSC ERROR: Signal received
>>>
>>> [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
>>> for trouble shooting.
>>>
>>> [0]PETSC ERROR: Petsc Release Version 3.7.2, unknown
>>>
>>> [0]PETSC ERROR: ./example-dbg on a arch-darwin-c-opt named
>>> mcswl091.mcs.anl.gov by xzhao Mon Jul 25 11:10:12 2016
>>>
>>> [0]PETSC ERROR: Configure options --with-cc=gcc --with-cxx=g++
>>> --with-fc=gfortran --download-mpich --download-fblaslapack
>>> --download-scalapack --download-mumps --download-superlu_dist
>>> --download-hypre --download-ml --download-metis --download-parmetis
>>> --download-triangle --download-chaco --with-debugging=0
>>>
>>> [0]PETSC ERROR: #1 User provided function() line 0 in  unknown file
>>>
>>> application called MPI_Abort(MPI_COMM_WORLD, 59) - process 0
>>>
>>>
>>>
>>
>>
>> --
>> 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
>>
>
>


-- 
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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