[petsc-dev] malloc_dump noise from threadcomm

[Jed Brown]

Sounds good to me.


On Sat, Dec 8, 2012 at 9:56 AM, Barry Smith <bsmith at mcs.anl.gov> wrote:

>
>    I don't think any of these three things are reasonable approaches. You
> are basically saying we should not log some memory usage because it is
> annoying.
>
>    Much better is to have something in addition to -malloc_dump (say
> -object_dump) that is more useful. Currently -malloc_dump is a cumbersome
> way of determining which objects has not be freed.
>
>     I propose an alternative:   every PetscHeaderCreate() log all the
> stack frames at which it is called and a list of all objects be maintained,
> any objects that are not destroyed can have their creation stack frames
> printed at the end making it easy to find the objects that were not
> destroyed. Then we will not recommend regular users use -malloc_dump (and
> that is reserved for us and will continue to log everything properly).
>
>    Note that PetscHeaderCreate() uses PetscLogObjectCreate() which can use
> PetscLogPHC() (stupid name) but is apparently now a black hole. We can just
> rework PetscLogObjectCreate() to save the stack frames.
>
>     Barry
>
> On Dec 8, 2012, at 9:29 AM, Jed Brown <jedbrown at mcs.anl.gov> wrote:
>
> > threadcomm.c has this thing
> >
> >   for (i=0;i<PETSC_KERNELS_MAX;i++) {
> >     ierr = PetscNew(struct
> _p_PetscThreadCommJobCtx,&PetscJobQueue->jobs[i]);CHKERRQ(ierr);
> >
> >
> > that gets freed when the last PetscObject gets destroyed. But if the
> user forgets to Destroy something, this shows up as a memory leak. Since
> the relevant malloc_dump output is much higher in the stack, this is
> confusing noise, and I'd like to eliminate it. We can either
> >
> > 1. not log this memory at all by calling malloc or posix_memalign
> directly
> >
> > 2. put code into PetscFinalize that ensures that this stuff has been
> freed (very messy if user does anything weird with communicators)
> >
> > 3. add way to mark PetscTrMalloc'd memory as "indirect" so that it is
> not reported by default
>
>
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