So, thanks to all for the help today. This note is to summarize what I have learned about the fabled Tk segfault.
When I finally managed to find a way to exhibit the problem under gdb, I found that the program was inside a pthread op. That was at a different computer than where I am now. As I recall, it was trying to unlock a mutex, and segfaulted. I've spent a little time trying to debug the xwin HAVE_PTHREAD code. I couldn't figure it out (yet). In the end, I found that you can throw -DHAVE_PTHREAD=off on the cmake line, and that cures the segfault. The Pthreads code in xwin, according to "git log -p", was written by Joao in the 2003 time frame. I know Tk has worked in release since then. I've been puzzling over this seemingly contradictory empirical result. Is it possible that HAVE_PTHREAD was an option in the code, but not enabled by default in the past, and that CBS was changed to enable it by default sometime in the last couple of years or so? In any event, my opinion is: 1) The pthread support is implicated. I believe there is a bug in mutex handling, though I haven't proven that by exhibiting a corrective patch yet. 2) The pthread code is suspect. Not to malign others' work, but in my attempts to review it today, I really could not convince myself that it even "looked right" to me. So, without meaning to sound over-the-top, I'm just saying, I'm suspicious that the pthread code isn't really worked out yet. 3) I think the CBS should be changed to keep HAVE_PTHREAD off by default, and list it as an experimental feature. A user/developer who wants to try it should be able to turn it on, but be warned that it is known to interact fatally with at least the Tk driver. Since the code in question is in xwin.c, there is also the possibility that it would negatively impact other X-only PLplot applications. 4) Tcl/Tk should stay on by default if CBS finds the needed stuff. -- It's been my intention to look into the threading support. This certainly accentuates in my own mind, the need for me to pick up this line of inquiry at some point, as soon as I can manage. But, I won't be able to do any more than this before the coming release. I hope this was at least a little bit helpful. -- Geoff ------------------------------------------------------------------------------ Crystal Reports - New Free Runtime and 30 Day Trial Check out the new simplified licensign option that enables unlimited royalty-free distribution of the report engine for externally facing server and web deployment. http://p.sf.net/sfu/businessobjects _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
