dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Fri, Jun 20, 2008 at 09:09:19AM +0100, Garth N. Wells wrote:
> 
> 
> Martin Sandve Alnæs wrote:
> > 2008/6/20 Garth N. Wells <gnw20@xxxxxxxxx>:
> >>
> >> Dag Lindbo wrote:
> >>> Hello!
> >>>
> >>> I attach a script that runs Valgrind (memcheck) on all C++ demos (based
> >>> on the one that just runs all demos). My suggestion is that this be
> >>> included in the testing procedure.
> >>>
> >>> At present (on my machine) 17 of 31 demos result in a memory leak (!)
> >>> None of the demos produce a memory error.
> >>>
> >>> Note that most, but not all, leaks are due to XML parsing. Are these
> >>> really leaks? It is impossible for vg to understand memory pools and
> >>> other exotic memory management that are not explicitly freed. Glib does
> >>> this in the GTS interface. Maybe libxml2 does something similar. In that
> >>> case, I can easily provide a suppression for xml2.
> >>>
> >> I took a look and fixed at least one leak, but a few others don't look
> >> like leaks to me. Part of the problem is that I think we're using
> >> pointers is some classes where std::vector would be more appropriate,
> >> particularly in the mesh and dof map classes, which is a source of
> >> potential leaks and makes ownership unclear.
> >>
> >> Is there a reason that we use pointers for various arrays in the mesh
> >> classes rather than std::vector?
> > 
> > I believe you cannot get the pointer to std::vector content?
> > (At least not safely and portable?)
> >
> 
> In many cases, this isn't needed. Pointers have been used for privare 
> arrays which are (re)sized at runtime and aren't passed around, e.g.
> 
>    uint* connections
> 
> in MeshConnectivity.

Yes, it's passed around. See for example operator() in MeshConnectivity:

 inline const uint* operator() (uint entity) const
 { return (entity < num_entities ? connections + offsets[entity] : 0); }

-- 
Anders


> > An alternative may be to use shared_ptr<real>,
> > if several classes are to use the same memory.
> > 
> > The main backsides are more template syntax
> > and no python support. The latest swig is supposed
> > to have support for using shared_ptr with python.
> > 
> > If you want to try shared_ptr for arrays, you need to
> > define an array deleter, I can dig up the code
> > if anyone's interested.
> > 
> 
> Smart pointers could be useful in some cases. Boost also provides some 
> elaborate smart pointers.
> 
> Garth
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