On 2012-12-06 18:12, Mark Atkinson wrote:
Short backstory, I had recently upgraded my workstation to the latest
current which included clang as default cc now.
...
qdbus under kde segfaults in malloc with a huge recursion stack:
[...]
#44740 0x282f7bd4 in QObject::QObject () from
/usr/local/lib/qt4/libQtCore.so.4
#44741 0x281cb649 in QAdoptedThread::QAdoptedThread () from
/usr/local/lib/qt4/libQtCore.so.4
#44742 0x281ce146 in QThreadData::current () from
/usr/local/lib/qt4/libQtCore.so.4
#44743 0x282f7bd4 in QObject::QObject () from
/usr/local/lib/qt4/libQtCore.so.4
#44744 0x281cb649 in QAdoptedThread::QAdoptedThread () from
/usr/local/lib/qt4/libQtCore.so.4
#44745 0x281ce146 in QThreadData::current () from
/usr/local/lib/qt4/libQtCore.so.4
#44746 0x282f7bd4 in QObject::QObject () from
/usr/local/lib/qt4/libQtCore.so.4
#44747 0x281cb649 in QAdoptedThread::QAdoptedThread () from
/usr/local/lib/qt4/libQtCore.so.4
#44748 0x281ce146 in QThreadData::current () from
/usr/local/lib/qt4/libQtCore.so.4
#44749 0x281cbc05 in QThread::currentThread () from
/usr/local/lib/qt4/libQtCore.so.4
#44750 0x28095d21 in QDBusConnectionPrivate::deleteYourself () from
/usr/local/lib/qt4/libQtDBus.so.4
#44751 0x28089634 in QDBusConnection::~QDBusConnection () from
/usr/local/lib/qt4/libQtDBus.so.4
#44752 0x0804b800 in __dtor__ZL10connection ()
#44753 0x28660417 in __cxa_finalize () from /lib/libc.so.7
#44754 0x2860747a in exit () from /lib/libc.so.7
#44755 0x0804c125 in main ()
(gdb)
This is a bug in qdbus; it uses a global static QDBusConnection object,
and the order in which global destructors are called is undefined:
http://qt.gitorious.org/qt/qttools/blobs/stable/src/qdbus/qdbus/qdbus.cpp#line57
In this particular case, the destructor (__dtor__ZL10connection) is
called *after* all of Qt's internal stuff has already been destroyed:
- QDBusConnectionPrivate::deleteYourself() tries to figure out if it is
called from the current QThread, and calls QThread::currentThread()
- QThread::currentThread() calls QThreadData::current()
- QThreadData::current() tries to instantiate a QAdoptedThread
- QAdoptedThread descends from QObject, so calls QObject::QObject()
- QObject::QObject() calls QThreadData::current()
- Endless loop results, until the stack is blown, and a new operator
fails in malloc()
The global static QDBusConnection object should be replaced by a
singleton, as suggested here:
http://techbase.kde.org/Policies/Library_Code_Policy#Static_Objects
but I am not sure how that is normally done in Qt itself.
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
