dolfin team mailing list archive

[Anders Logg <logg@xxxxxxxxx>]

On Thu, Dec 03, 2009 at 12:24:53AM +0000, Garth N. Wells wrote:
>
>
> Anders Logg wrote:
> > On Wed, Dec 02, 2009 at 01:53:04PM +0100, Johannes Ring wrote:
> >>>>>>>>>> I can't figure out why these fail. Valgrind does not complain on my
> >>>>>>>>>> machine. Does anyone have a 32 bit system to test on?
> >>>>>>>>> Yes, I have my laptop. I will try to do some debugging.
> >>>>>>>> I got a segfault too. Here is the output from running
> >>>>>>>> demo\pde\stokes\stabilized\cpp in gdb:
> >>>>>>>>
> >>>>>>>> johannr@simula-x61:cpp$ gdb ./demo
> >>>>>>>> GNU gdb 6.8-debian
> >>>>>>>> Copyright (C) 2008 Free Software Foundation, Inc.
> >>>>>>>> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> >>>>>>>> This is free software: you are free to change and redistribute it.
> >>>>>>>> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> >>>>>>>> and "show warranty" for details.
> >>>>>>>> This GDB was configured as "i486-linux-gnu"...
> >>>>>>>> (gdb) run
> >>>>>>>> Starting program:
> >>>>>>>> /home/johannr/src/bzr/dolfin/demo/pde/stokes/stabilized/cpp/demo
> >>>>>>>> [Thread debugging using libthread_db enabled]
> >>>>>>>> [New Thread 0xb536a6c0 (LWP 21306)]
> >>>>>>>> Solving linear variational problem
> >>>>>>>>   Matrix of size 8604 x 8604 has 174636 nonzero entries.
> >>>>>>>>   Applying boundary conditions to linear system.
> >>>>>>>>   Applying boundary conditions to linear system.
> >>>>>>>>
> >>>>>>>> Program received signal SIGSEGV, Segmentation fault.
> >>>>>>>> [Switching to Thread 0xb536a6c0 (LWP 21306)]
> >>>>>>>> 0xb7c265c8 in dolfin::Data::clear () from
> >>>>>>>> /home/johannr/src/bzr/dolfin/local/lib/libdolfin.so.0
> >>>>>>>> Current language:  auto; currently asm
> >>>>>>>> (gdb) where
> >>>>>>>> #0  0xb7c265c8 in dolfin::Data::clear () from
> >>>>>>> The line
> >>>>>>>
> >>>>>>>  x.resize(0);
> >>>>>>>
> >>>>>>> in the function Data::clear() in dolfin/function/Data.cpp looks
> >>>>>>> suspicious. Could you try replacing that line with
> >>>>>>>
> >>>>>>>  x.clear();
> >>>>>>>
> >>>>>>> and see if that helps?
> >>>>>> No, it didn't help.
> >>>>> ok, can you some other things, like not calling clear() from the
> >>>>> previous location in the trace. And if that works, then comment out
> >>>>> the lines in clear() one by one.
> >>>> When I comment out line 62 in dolfin/function/GenericFunction.cpp, the
> >>>> stokes/stabilized demo seems to be running "forever" (I killed it
> >>>> after ten minutes).
> >>> Strange...
> >>>
> >>> Is there some virtual machine or host I could get access to so I can
> >>> debug it?
> >> Yes, for instance gogmagog.simula.no or kangchenjunga.simula.no. Or I
> >> can give you access to the hardy-i386 buildbot slave if you prefer.
> >>
> >> Johannes
> >
> > I've been spending a few hours on this so for without any luck. It's
> > difficult to spot what goes wrong. It's one of those cases where it
> > suddenly works if I print too much debug information...
> >
> > I'll keep searching but any suggestions appreciated. This is the last
> > remaining issue before the release.
> >
>
> The change
>
>   http://bazaar.launchpad.net/~dolfin-core/dolfin/main/revision/4370
>
> hopefully fixes this bug.

Great! I've confirmed that it works now on the i386 buildbot.

This should have been caught by a check in DirichletBC. I've added on
now to catch this.

--
Anders

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