[vtkusers] vtkTkRenderWidget:Linux:Python and VTK threaded:each render spawns zombie

[Brent Goodrick]

Hi Donna,

You are building on RH 6.1 and executing on RH 8.0 which is bad news.
GLIBC has changed, name mangling in the compiler has changed,
etc. etc.  I would suggest compiling under the same system
(compiler+libraries+OSrevision) in which you execute on.  

If you are bound and determined to do it, you may try the
compatibility libraries that Red Hat has shipped in the past (RH 7.x
anyhow).  I expect that they would discontinue those libraries at some
point, so that would not be a good long term strategy.

Brent Goodrick
PT Software

>>>>> "donna" == donna  <donna at v1.wustl.edu> writes:

donna> Build environment:
donna> 	Linux RedHat 6.1 (Cartman) 2.2.12-20 (uni-processor)
donna> 	gcc 3.2.2
donna> 	Python 2.1.3
donna> 	VTK cvs co -D "10/5/2002"
donna> 	both python and vtk configured with threads

donna> When I run the following simple python script on a dual processor host
donna> running Linux RedHat 8.0 (Psyche) 2.4.18-26.8.0smp, each render spawns a
donna> zombie python process:

donna> http://pulvinar.wustl.edu/donna/SureFit/Linux/volview.py

donna> (This script is a simplified version of
donna> http://public.kitware.com/cgi-bin/cvsweb.cgi/VTK/Examples/Medical/Python/Medical3.py;
donna> thanks to will and prabhu for making it available.)

donna> Keypress 'i' or 'd' in the image widget (increment or decrement the
donna> slice displayed from VTK_DATA_ROOT + "/Data/headsq/quarter") triggers a
donna> vtkTkRenderWidget render.  Running python in gdb, with several printf
donna> messages inserted into VTK/Common/vtkDataObject.cxx and
donna> VTK/Common/vtkImageData.cxx, produces this output:

donna> *** DISPLAYING slice 30
donna> ...vtkImageData::UpdateData ...
donna> ...vtkDataObject::UpdateData begin...
donna> ...propagate the UpdateData to the source...
...Source-> UpdateData...
donna> ...vtkImageData::UpdateData ...
donna> ...vtkDataObject::UpdateData begin...
donna> ...vtkDataObject::UpdateData end...
donna> ...checking this->UpdateNumberOfPieces == 1 ...
donna> ...confirmed this->UpdateNumberOfPieces == 1 ...
donna> [New Thread 24580 (LWP 668)]
...this-> UpdatePiece...
...this-> UpdateNumberOfPieces...
...this-> UpdateGhostLevel...
donna> ...vtkDataObject::UpdateData end...
donna> ...checking this->UpdateNumberOfPieces == 1 ...
donna> ...confirmed this->UpdateNumberOfPieces == 1 ...

donna> The modified versions of vtkDataObject.cxx and vtkImageData.cxx are here
donna> -- just printf statements added to see where the thread is being
donna> spawned:

donna> http://pulvinar.wustl.edu/donna/SureFit/Linux/vtkDataObject.cxx
donna> http://pulvinar.wustl.edu/donna/SureFit/Linux/vtkImageData.cxx

donna> The thread is being spawned when vtkImageData::UpdateData returns to
donna> vtkDataObject::UpdateData, because this->UpdateNumberOfPieces == 1. 
donna> There seems to be some recursion here.  Can anyone help me understand
donna> why python is spawning a new thread here?  These threads look like this
donna> in ps -efl output:

donna> 044 Z donna     1590  1589  0  75   0    -     0 do_exi 10:59 pts/2   
donna> 00:00:00 [python <defunct>]
donna> 044 Z donna     1591  1589  0  80   0    -     0 do_exi 10:59 pts/2   
donna> 00:00:00 [python <defunct>]
donna> 044 Z donna     1592  1589  0  80   0    -     0 do_exi 10:59 pts/2   
donna> 00:00:00 [python <defunct>]
donna> 044 Z donna     1593  1589  0  76   0    -     0 do_exi 10:59 pts/2   
donna> 00:00:00 [python <defunct>]

donna> They have caused crashes for one user, whose soft maxproc limit is
donna> 1024.  My application has numerous render events, and in his case
donna> several threads are being spawned per render.  When the number of
donna> zombies approaches 1000, my application crashes.  This seems to happen
donna> despite increasing the maxproc limit.  (Python seems to be crashing at
donna> the machine's soft limit, regardless of the user's environment.)

donna> I can rebuild python and vtk without threads, and the user doesn't
donna> crash.  But I'd like to understand why the renders are spawning these
donna> threads.  Any ideas are appreciated.

donna> Thanks,

donna> Donna Hanlon
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