[Python-apps-team] Bug#478844: Bug#478844: mayavi2: segfaults or corrupts memory after some operations

[Francesco Poli]

On Mon, 05 May 2008 23:53:26 +0530 Prabhu Ramachandran wrote:

[...]
> On my Mac (which is all I have access to on my "vacation"), I was able 
> to reproduce the problem nicely thank to the data that Francesco has 
> provided.

Just for the record, I was able to reproduce the bug on a lenny/testing
i386 box.
I mean, *before applying your proposed bug fix*, so don't panic!  ;-)

I performed the described steps, including the copy operation
which seemed to work.  Then, as soon as I performed the paste
operation, MayaVi2 became totally unresponsive (basically frozen:
GUI elements and panes were not updated anymore) and the
following error message appeared on the terminal:

*** glibc detected *** python: double free or corruption (out):
0x0a31fb00 ***

At that point, I had to

$ kill -TERM 13230

(where 13230 was mayavi2's PID) from another terminal...

> I think I have a fix.  Can you replace your copy of the 
> PLOT3DReader in the sources directory of your installed mayavi2 with the 
> attached and try again?
> 
> What this does is to pop up a UI as soon as the reader is initialized 
> and before the files are read giving you a chance to set the properties.

I think this is a great idea!

>   With that I am able to reliably open up your data files.  If not it 
> tries to be graceful but can die if fed enough poison and this is solely 
> due to the VTK reader not behaving correctly.  There is little I can do 
> about that.

Well, if, in some situations, the VTK reader behaves the wrong way,
there _is_ something you could do, to be precise: contact VTK upstream
authors (KitWare) and help them fix the issue.
But anyway...

> 
> Please try this and let me know that it works and I'll check it in to 
> both the branches and trunk.

I've tried your modified plot3d_reader.py on the above mentioned i386
box.  This is a _huge_ step forward: now I am able to copy and paste
PLOT3D:tiny.xyz, tiny.q    :-)

I've noticed a problem, though.  :-(

The MayaVi pane looks like:

 * TVTK Scene 1
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * Surface
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * Surface

Suppose I delete the Surface module from one of two subtrees:

 * TVTK Scene 1
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * Surface
   * PLOT3D:tiny.xyz, tiny.q
     * Modules

then left-click on the (now childless) Modules entry
and choose Visualize -> Modules -> ContourGridPlane from
menus:

 * TVTK Scene 1
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * Surface
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * ContourGridPlane

At this point, as soon as I left-click on the ContourGridPlane
module, I get a debugger window (see attached screenshot inspector.png)
and cannot see any ContourGridPlane properties in the MayaVi
object editor pane...

This problem has been seen on both my amd64 box and the above-mentioned
i386 box.

Unfortunately, I didn't manage to find the time to investigate further,
that's why I decided to take a screenshot.

Please note that ContourGridPlane seems to work as expected, if
I start mayavi2 and avoid copying/pasting data sources, that is
to say as in:

 * TVTK Scene 1
   * PLOT3D:tiny.xyz, tiny.q
     * Modules
       * ContourGridPlane


> 
> Thanks for the bug reports and patience.

_I_ have to really thank _you_ for your kind responses to bug reports
and for your help in fixing the issues that currently make mayavi2
unusable for me (unfortunately).


-- 
 http://frx.netsons.org/doc/index.html#nanodocs
 The nano-document series is here!
..................................................... Francesco Poli .
 GnuPG key fpr == C979 F34B 27CE 5CD8 DC12  31B5 78F4 279B DD6D FCF4

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