dolfin team mailing list archive

["Garth N. Wells" <gnw20@xxxxxxxxx>]

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.

Garth

> --
> Anders
> 
> 
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