leaks in multiple calls for preallocating AIJ matrices

[Lisandro Dalcin]

I have the fix almost ready, but a new issue arises and I want to know
your opinions

What to do if MatXXXSetPreallocation() is called after a matrix was
assembled? Should we generate an error? See the behavior of this in
action with a simple python snipet of code:

A = PETSc.Mat().create()
A.setSizes([5,5])
A.setFromOptions()
A.setPreallocation(nz=3)
for i in range(5): A[i,i] = 1
A.assemble()
A.view()
print
A.setPreallocation(nz=3)
A.view()

the output of this is

row 0: (0, 1)
row 1: (1, 1)
row 2: (2, 1)
row 3: (3, 1)
row 4: (4, 1)

row 0: (0, 0)  (0, 0)  (0, 0)
row 1: (0, 0)  (0, 0)  (0, 0)
row 2: (0, 0)  (0, 0)  (0, 0)
row 3: (0, 0)  (0, 0)  (0, 0)
row 4: (0, 0)  (0, 0)  (0, 0)

The matrix structure is completely broken. The easiest way to go is
not enable users to reset preallocation if the matrix was ever
assembled.

What do you think?


On 10/23/07, Barry Smith <bsmith at mcs.anl.gov> wrote:
>
>   Fine.
>
> On Tue, 23 Oct 2007, Lisandro Dalcin wrote:
>
> > Of course, the space that can be reutilized are the arrays with
> > preallocation info, not the ones with actual matrix entries (a,i,j).
> >
> > On 10/23/07, Lisandro Dalcin <dalcinl at gmail.com> wrote:
> > > Looking at the actual code, it seems there is not need to actually
> > > reallocate space, the same space can be reutilized. Do you think I'm
> > > missing something?
> > >
> > > And please, tell me: should I fix this in release-2.3.3? I believe
> > > this will not impact previous user code in any way.
> > >
> > >
> > >
> > > On 10/23/07, Barry Smith <bsmith at mcs.anl.gov> wrote:
> > > >
> > > >   Lisandro,
> > > >
> > > >     I agree we should support multiple calls (or at worst generate an
> > > > error on the second call). Presumably the specific
> > > > MatXXXYYYSetPreallocation() routines would simply free up their
> > > > current points and then (as it does now) allocate the appropriate new
> > > > space. Feel free to add this.
> > > >
> > > >    Barry
> > > >
> > > >
> > > > On Mon, 22 Oct 2007, Lisandro Dalcin wrote:
> > > >
> > > > > Currently, making sucessive calls for preallocating AIJ matrices seem
> > > > > to originate memory leaks.
> > > > >
> > > > > How should this be corrected? I would prefer that this is a valid
> > > > > operation, and fix appropriate routines to deallocate/reuse previous
> > > > > memory, and set the new user-specified preallocation data.
> > > > >
> > > > > Other point: should this fix go to release-2.3.3?
> > > > >
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> > > --
> > > Lisandro Dalcín
> > > ---------------
> > > Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
> > > Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
> > > Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
> > > PTLC - Güemes 3450, (3000) Santa Fe, Argentina
> > > Tel/Fax: +54-(0)342-451.1594
> > >
> >
> >
> >


-- 
Lisandro Dalcín
---------------
Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC)
Instituto de Desarrollo Tecnológico para la Industria Química (INTEC)
Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
PTLC - Güemes 3450, (3000) Santa Fe, Argentina
Tel/Fax: +54-(0)342-451.1594