[petsc-dev] Pairing DM{Get/Restore}GlobalVector() before/after SNESSolve() breaks vinewtonrsls

[Ed Bueler]

O.k., I will just avoid holding it in that way.

Unfortunately, the man page

http://www.mcs.anl.gov/petsc/petsc-current/docs/manualpages/DM/DMGetGlobalVector.html

gives no hint that a "complicated PETSc solver", a presumably well-defined
phrase ;-), interferes with this particular DM functionality.

Ed


On Wed, Apr 29, 2015 at 9:57 PM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>   To quote Steve Jobs, you are using it wrong :-)
>
>    The DMGetXXX routines are not intended to be used to obtain vectors
> that are kept around while complicated PETSc solvers are being used. They
> are for obtaining work vectors for example for a function evaluation inside
> an ODE or nonlinear solver call. If you plan to keep it around you should
> use the Create versions.
>
>   Barry
>
> > On Apr 29, 2015, at 2:38 PM, Ed Bueler <elbueler at alaska.edu> wrote:
> >
> > Dear Petsc --
> >
> > The patch at bottom is off of current master.  Applying it shows that in
> SNES example ex9.c the rsls version of SNESVI breaks.  Note that "./ex9
> -snes_type vinewtonssls" does not break.
> >
> > The expected behavior is no change, but the actual behavior with the
> patched version gives a "Clearing DM of global vectors that has a global
> vector obtained with DMGetGlobalVector()" message.  That is,
> >
> > $ ./ex9
> > setup done: grid  Mx,My = 11,11  with spacing  dx,dy = 0.4000,0.4000
> > [0]PETSC ERROR: --------------------- Error Message
> --------------------------------------------------------------
> > [0]PETSC ERROR: Object is in wrong state
> > [0]PETSC ERROR: Clearing DM of global vectors that has a global vector
> obtained with DMGetGlobalVector()
> > [0]PETSC ERROR: See http://www.mcs.anl.gov/petsc/documentation/faq.html
> for trouble shooting.
> > [0]PETSC ERROR: Petsc Development GIT revision: v3.5.3-2797-g27699ca
> GIT Date: 2015-04-27 23:20:45 -0500
> > [0]PETSC ERROR: ./ex9 on a linux-c-opt named bueler-leopard by ed Wed
> Apr 29 13:34:36 2015
> > [0]PETSC ERROR: Configure options --download-mpich --with-debugging=0
> > [0]PETSC ERROR: #1 DMClearGlobalVectors() line 196 in
> /home/ed/petsc/src/dm/interface/dmget.c
> > [0]PETSC ERROR: #2 DMSetVI() line 238 in
> /home/ed/petsc/src/snes/impls/vi/rs/virs.c
> > [0]PETSC ERROR: #3 SNESSolve_VINEWTONRSLS() line 461 in
> /home/ed/petsc/src/snes/impls/vi/rs/virs.c
> > [0]PETSC ERROR: #4 SNESSolve() line 3884 in
> /home/ed/petsc/src/snes/interface/snes.c
> > [0]PETSC ERROR: #5 main() line 103 in
> /home/ed/petsc/src/snes/examples/tutorials/ex9.c
> > [0]PETSC ERROR: No PETSc Option Table entries
> > [0]PETSC ERROR: ----------------End of Error Message -------send entire
> error message to petsc-maint at mcs.anl.gov----------
> > application called MPI_Abort(MPI_COMM_WORLD, 73) - process 0
> > [unset]: aborting job:
> > application called MPI_Abort(MPI_COMM_WORLD, 73) - process 0
> >
> >
> > Note that all I have done is use DMGetGlobalVector() on the DM for a
> dummy vector.  I guess that since the SNES messes with the DM things get
> confused.
> >
> > An easy workaround is to use DMCreateGlobalVector() or VecDuplicate()
> etc., so no crisis.
> >
> > Generally rsls is doing heroic work for me, so no serious complaints.
> >
> > Ed
> >
> >
> >
> > From c9a0f2dd913b3a0ab3cf39379d9361d10d22a2b4 Mon Sep 17 00:00:00 2001
> > From: Ed Bueler <elbueler at alaska.edu>
> > Date: Wed, 29 Apr 2015 13:29:02 -0600
> > Subject: [PATCH] Pairing DM{Get/Restore}GlobalVector() before/after
> >  SNESSolve() breaks vinewtonrsls.
> >
> > ---
> >  src/snes/examples/tutorials/ex9.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/src/snes/examples/tutorials/ex9.c
> b/src/snes/examples/tutorials/ex9.c
> > index ca4d344..3afa8b9 100644
> > --- a/src/snes/examples/tutorials/ex9.c
> > +++ b/src/snes/examples/tutorials/ex9.c
> > @@ -96,9 +96,14 @@ int main(int argc,char **argv)
> >    ierr = PetscPrintf(PETSC_COMM_WORLD,"setup done: grid  Mx,My = %D,%D
> with spacing  dx,dy = %.4f,%.4f\n",
> >                       info.mx
> ,info.my,4.0/(PetscReal)(info.mx-1),4.0/(PetscReal)(info.my-1));CHKERRQ(ierr);
> >
> > +Vec foo;
> > +ierr = DMGetGlobalVector(da,&foo);CHKERRQ(ierr);
> > +
> >    /* solve nonlinear system */
> >    ierr = SNESSolve(snes,NULL,u);CHKERRQ(ierr);
> >
> > +ierr = DMRestoreGlobalVector(da,&foo);CHKERRQ(ierr);
> > +
> >    /* compare to exact */
> >    ierr = VecAXPY(u,-1.0,user.uexact);CHKERRQ(ierr); /* u <- u - uexact
> */
> >    ierr = VecNorm(u,NORM_1,&error1);CHKERRQ(ierr);
> > --
> > 1.9.1
> >
> >
> > --
> > Ed Bueler
> > Dept of Math and Stat and Geophysical Institute
> > University of Alaska Fairbanks
> > Fairbanks, AK 99775-6660
> > 301C Chapman and 410D Elvey
> > 907 474-7693 and 907 474-7199  (fax 907 474-5394)
>
>


-- 
Ed Bueler
Dept of Math and Stat and Geophysical Institute
University of Alaska Fairbanks
Fairbanks, AK 99775-6660
301C Chapman and 410D Elvey
907 474-7693 and 907 474-7199  (fax 907 474-5394)
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