<div dir="ltr">vtkObject derived objects are not safe to access from multiple threads simultaneously. And since most of the KWWidgets objects derive from vtkObject... so the same is true for them.<br><br>vtkObject methods will execute on whatever thread you call them on. They are only guaranteed to work properly if you do all the access in a synchronized manner, using some sort of mutex mechanism to restrict access to a single thread at a time.<br>
<br>Best to avoid (*ahem*) stupid programming errors, I guess.<br><br>:-)<br>David<br><br><br><div class="gmail_quote">On Sun, Aug 31, 2008 at 12:45 PM, Peter Wainwright <span dir="ltr"><<a href="mailto:prw@ceiriog.eclipse.co.uk">prw@ceiriog.eclipse.co.uk</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hi,<br>
<br>
I have a Python application which handles images. It uses a KWWidgets<br>
application and main window. By a stupid programming error (ahem...) I<br>
triggered an error during rendering. This caused the program to crash<br>
out with SIGSEGV. Examining the core dump (see the attachment) I found<br>
that VTK/KWWidgets was trying to handle the original error when the<br>
segfault occurred.<br>
<br>
Thread 1 (the thread in which the segfault occurred) was cloned from<br>
Thread 3 (the main thread). However, in the cloned thread, winPtr =<br>
Tk_MainWindow(interp) is NULL.<br>
<br>
My questions are:<br>
<br>
(1) Is it supposed to be legal to do Tk-related stuff in a thread like<br>
this (I know many widgets sets are not thread-safe)<br>
<br>
and<br>
<br>
(2) If this is not legal, why is VTK trying to invoke the error handler<br>
in the context of the sub-thread? Should it not somehow pass the error<br>
back to the main thread for processing?<br>
<br>
I am working with recent CVS head versions of VTK and KWWidgets on<br>
Ubuntu 8.04<br>
<br>
Thank you,<br>
<font color="#888888"><br>
Peter Wainwright<br>
<br>
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