[Trilinos-Users] Problems with Teuchos::XMLObject memory management?

[Kevin Long]

Hi Jonas,

I'm not sure what could be causing the problem. If you still can't find the 
problem after a clean rebuild and valgrind/purify, perhaps you could send me 
a stripped-down example showing the problem and I could have a go at 
debugging it. I'm the guy who originally wrote the class, and so would be 
happy to try to fix it. It's been years since I wrote it so it's hardly fresh 
in my mind, but I can probably figure out how it works :-).

As Ross said, this class is used heavily without incident so I'd be surprised 
if there's a problem; however, it may be you're using some not-often-used 
feature in which a bug has lurked silently for years.  

Let me know how it goes, and drop a line if you need me to help with the 
debugging. 

Kevin



On Monday 03 March 2008 07:19, Bartlett, Roscoe A wrote:
> Hello Jonas,
>
> The class XMLObject is a handle class that does shallow copies of the
> XMLObjectImplen data by default.  That is why where is no specifically
> defined copy constructor or assignment operator, or destructor; the
> compiler-generated versions should do exactly the right thing since only a
> single Teuchos::RCP is being stored as private data.  When you use a
> shallow-copy handle class you have to be very careful about sharing issues
> and call deepCopy() when that is what you want.  I did not write this class
> and there is just one simple unit test for it (see
> teuchos/test/XML/cxx_main.cpp) but this class has seen very heavy use in
> the last few years and we have need seen issues like what you describe.
>
> Have you run valgrind or purify on your program?  The final segfault that
> you are seeing might be a result of other code that is corrupting the data
> of the XMLObject[Implem] objects.  The first that you should always do when
> you get a segfault is to delete all of the *.o, *.a, and *.exe files and
> rebuild everything from scratch.  That fixes about 50% of the segfaults
> that I have seen in the past.
>
> I hope some of these ideas help,
>
> Ross
>
> -----Original Message-----
> From: trilinos-users-bounces at software.sandia.gov
> [mailto:trilinos-users-bounces at software.sandia.gov] On Behalf Of Jonas
> Thies Sent: Monday, March 03, 2008 2:14 AM
> Cc: trilinos-users at software.sandia.gov
> Subject: [Trilinos-Users] Problems with Teuchos::XMLObject memory
> management?
>
> Hi all,
>
> I'm trying to put together a fairly complicated XML structure to be used as
> the 'light-weight' part of an Xdmf output format. All goes well until the
> end of the run, when the XMLObject is being deleted, whereupon I get a
> coredump. It seems that there is an issue with the internal std::vector
> destructor. When I put everything in one main program it works, I suspect
> it has to do with the way new XMLObjects are copied into the vector. I
> noticed that there is a method 'deepCopy', but no copy constructor, which
> might explain the behaviour (std::vector push_back calls the copy
> constructor). Am I doing something wrong? I'm surprised it works for the
> XMLParameterListWriter class. Is there an example somewhere? By the way,
> I'm working with Trilinos version 8.0.1
>
> thanks for your help,
> Jonas
>
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-- 
Dr. Kevin Long
Department of Mathematics and Statistics
Texas Tech University
Lubbock TX 79409
kevin.long at ttu.edu