The problem appears to be that in KstVCurve::paint the vectors are locked in a defined order (namely xv, yv, [exv], [eyv], [exmv], [eymv]) while in KstVCurve::update (which uses KstdataObject::writeLockInputsAndOutputs for the actualt locking) the order may be different.

The solution is to lock the vectors in the same order in both cases, else we face a potential deadlock.

SVN commit 1137113 by arwalker:

CCBUG:241273 This should solve the deadlock issue, by ensuring that all of the locks are obtained in one thread before any of the locks are obtained in the other. Will leave the bug report open for a while to allow for testing.

 M  +3 -1      kstdataobject.cpp  
 M  +2 -1      kstdataobject.h  
 M  +6 -0      kstvcurve.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1137113

Does this possibly also exist in kst 2.x?

I upgraded to svn 1137746 but I still see a deadlock if I resize the kst window a few times after step 10:

Thread 2 (Thread 0x7f784b483710 (LWP 16173)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007f7856c96df2 in KstWaitCondition::wait(QMutex*, unsigned long) () from /home/lindi/scm/graphics/kst/src/libkst/libkstbase.so.1
#2  0x00007f7856c59ae9 in KstRWLock::writeLock() const () from /home/lindi/scm/graphics/kst/src/libkst/libkstbase.so.1
#3  0x00007f7856efcab4 in KstDataObject::writeLockInputsAndOutputs() () from /home/lindi/scm/graphics/kst/src/libkstmath/libkstmath.so.1
#4  0x00007f7856f184b5 in KstVCurve::update(int) () from /home/lindi/scm/graphics/kst/src/libkstmath/libkstmath.so.1
#5  0x00007f7857c0a85b in UpdateThread::doUpdates(bool, bool*) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#6  0x00007f7857c0bd26 in UpdateThread::run() () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#7  0x00007f7854685e5b in QThreadInstance::start(void*) () from /usr/lib/libqt-mt.so.3
#8  0x00007f78502418ba in start_thread (arg=<value optimized out>) at pthread_create.c:300
#9  0x00007f7854ec801d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#10 0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f785815f760 (LWP 16157)):
#0  __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:136
#1  0x00007f78502440e9 in _L_lock_953 () from /lib/libpthread.so.0
#2  0x00007f7850243f0b in __pthread_mutex_lock (mutex=0x13f01a8) at pthread_mutex_lock.c:61
#3  0x00007f785495fd7d in QRealMutexPrivate::lock() () from /usr/lib/libqt-mt.so.3
#4  0x00007f7856f1a6e0 in KstVCurve::paint(KstCurveRenderContext const&) () from /home/lindi/scm/graphics/kst/src/libkstmath/libkstmath.so.1
#5  0x00007f7857b24729 in Kst2DPlot::draw(KstPainter&) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#6  0x00007f7857b24e83 in Kst2DPlot::draw() () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#7  0x00007f7857b24f40 in Kst2DPlot::updateSelf() () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#8  0x00007f7857b63b2d in KstViewObject::paintUpdate() () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#9  0x00007f7857b66ca3 in KstViewObject::paint(KstPainter&, QRegion const&) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#10 0x00007f7857b67124 in KstViewObject::paint(KstPainter&, QRegion const&) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#11 0x00007f7857b7b0af in KstTopLevelView::paint(KstPainter::PaintType, QRegion const&) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#12 0x00007f7857b7b19b in KstTopLevelView::paint(KstPainter::PaintType) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#13 0x00007f7857b5ea91 in KstViewWidget::paintEvent(QPaintEvent*) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#14 0x00007f7857b0a3b5 in Kst2DPlot::wheelEvent(QWidget*, QWheelEvent*) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#15 0x00007f7857b6147f in KstViewWidget::wheelEvent(QWheelEvent*) () from /home/lindi/scm/graphics/kst/src/libkstapp/libkstapp.so.1
#16 0x00007f785471ce30 in QWidget::event(QEvent*) () from /usr/lib/libqt-mt.so.3
#17 0x00007f785468b725 in QApplication::internalNotify(QObject*, QEvent*) () from /usr/lib/libqt-mt.so.3
#18 0x00007f785468cae3 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libqt-mt.so.3
#19 0x00007f785692b4a4 in KApplication::notify(QObject*, QEvent*) () from /usr/lib/libkdecore.so.4
#20 0x00007f7854620bec in QETWidget::translateWheelEvent(int, int, int, int, Qt::Orientation) () from /usr/lib/libqt-mt.so.3
#21 0x00007f785462af49 in QETWidget::translateMouseEvent(_XEvent const*) () from /usr/lib/libqt-mt.so.3
#22 0x00007f7854629d68 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/libqt-mt.so.3
#23 0x00007f785463c35a in QEventLoop::processEvents(unsigned int) () from /usr/lib/libqt-mt.so.3
#24 0x00007f78546a1fa1 in QEventLoop::enterLoop() () from /usr/lib/libqt-mt.so.3
#25 0x00007f78546a1e62 in QEventLoop::exec() () from /usr/lib/libqt-mt.so.3
#26 0x000000000040d493 in main ()

This I can reproduce, without the need for steps 3 to 11 inclusive.

SVN commit 1138336 by arwalker:

CCBUG:241273 lock all the inputs to a KstVCurve::paint at the same time, to avoid a potential deadlock

 M  +24 -26    kstvcurve.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1138336

Am now unable to reproduce the deadlock.