Andrew Ross wrote: > On Thu, Mar 12, 2009 at 05:13:11PM -0700, Alan Irwin wrote: > My results were with 9730 so included Alban's fixes and I still see > the memory management issues with familying on my Kubuntu Intrepid > system (current stable release). > > With the current svn revision (r9732) I am getting > *** glibc detected *** ./x02c: double free or corruption (!prev): > 0x08e3cb90 *** > with example 2. > > If it works for you I can see two possible causes > > 1) Still issues with cmake 2.6.0. Things now compile and work after a > fashion, but I still get a warning message from moc > [ 72%] Generating moc_qt.cxx > /home/andrew/software/plplot/plplot/drivers/qt.h:0: Warning: No > relevant classes found. No output generated. > > 2) It's a QT issue. (I've got version 4.4.3). > > I think it might be the latter. > > The problem is that the first time through the code path qApp is > deleted, but is not set to NULL. You can't do this since qApp is not > actually a static function which returns the instance of QAppliction. > In my version of QT at least, deleting this does not result in a NULL > qApp pointer and so new QApplication is not called for the second > call to initQtApp. As a result qApp is still referring to the "old" > qApp pointer and so the second call to closeQtApp leads to a double > free when calling delete qApp. > > I don't understand how the current code works for you, and to me this > looks like a dodgy way of doing things. Perhaps it is "fixed" in a > later version of libqt4. > > Not being a QT expert I don't understand precisely how qApp is working. > Is it really necessary to create a new QAppliction for every page? Seems > unlikely. > > Actually, it seems to be the delete qApp that is causing the problem. > There is something strange going on. If I delete qApp, then the next > call to new QApplication returns exactly the same pointer as the first > call, even though qApp is NULL just before the second call to new. > This would be very unlikely if it was genuinely returning a new > object. I think this may be a libqt4bug here. If I comment out the > call to delete qApp and remove the checks on qApp being NULL then > everything works correctly, but I wonder if there are then memory > leaks since I do get new instance of QApplication for each call to > initQApp. > > Alan, Alban, what versions of libq4t are you using? > > Of course it could still be related to the cmake 2.6.0 issues. I will > get and build cmake 2.6.3 later to check. I'm surprised that it build > at all though if this is an issue. > > Cheers > > Andrew > > ------------------------------------------------------------------------------ > Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are > powering Web 2.0 with engaging, cross-platform capabilities. Quickly and > easily build your RIAs with Flex Builder, the Eclipse(TM)based development > software that enables intelligent coding and step-through debugging. > Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com > _______________________________________________ > Plplot-devel mailing list > Plplot-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/plplot-devel
Hi Andrew, Actually, it was quite tricky to make the Qt drivers work in an autonomous way, as Qt applications are not usually built like that. What I've done is that calls to plD_init_whatever increments a counter and, if this counter was 0 and no QApplication defined, a QApplication is created. When calling plD_tidy, the counter is decremented, and the last running device deletes the QApplication. Thus there should be only one QApplication running at one point. I'm not sure I was supposed to delete qApp, which is a special Qt variable. Usually, one does not do that (qApp is created in main() and main returns app.exec()), but I did it as I believe it was good practice for memory management, and as it didn't raise any issue on my system (kubuntu 64 8.10). As for your moc not producing anything, actually since yesterday's release it's normal. We could remove this call to moc, but it may prove useful in the future. I'll see what I can do. Alban ------------------------------------------------------------------------------ Apps built with the Adobe(R) Flex(R) framework and Flex Builder(TM) are powering Web 2.0 with engaging, cross-platform capabilities. Quickly and easily build your RIAs with Flex Builder, the Eclipse(TM)based development software that enables intelligent coding and step-through debugging. Download the free 60 day trial. http://p.sf.net/sfu/www-adobe-com _______________________________________________ Plplot-devel mailing list Plplot-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/plplot-devel
