Version:           unspecified (using KDE 4.7.0) 
OS:                Linux

I get occasional UI freezes of several seconds. There are serious performance problems, these are discussed in different reports, but may be related.
The freeze resolves eventually, apparently there is a synchronous wait operation in the main thread.

I attached gdb a few times and reproducibly got this backtrace:



#0  0x00007f58cd70d503 in poll () from /lib64/libc.so.6
#1  0x00007f58c414ae00 in ?? () from /lib64/libdbus-1.so.3
#2  0x00007f58c4149cfd in ?? () from /lib64/libdbus-1.so.3
#3  0x00007f58c4134745 in ?? () from /lib64/libdbus-1.so.3
#4  0x00007f58c4135ab3 in ?? () from /lib64/libdbus-1.so.3
#5  0x00007f58cac4da05 in q_dbus_pending_call_block (this=0x62ca50, pcall=0x286b1fc0) at qdbus_symbols_p.h:305
#6  QDBusConnectionPrivate::waitForFinished (this=0x62ca50, pcall=0x286b1fc0) at qdbusintegrator.cpp:1739
#7  0x00007f58cac8bb63 in QDBusPendingCallPrivate::waitForFinished (this=0x286b1fc0) at qdbuspendingcall.cpp:242
#8  0x00007f58b43b5ab9 in MailCommon::FolderCollection::identity() const () from /usr/lib64/libmailcommon.so.4
#9  0x00007f58b46d15d0 in ?? () from /usr/lib64/libkmailprivate.so.4
#10 0x00007f58b39c95df in MessageList::StorageModel::containsOutboundMessages() const () from /usr/lib64/libmessagelist.so.4
#11 0x00007f58b398033d in ?? () from /usr/lib64/libmessagelist.so.4
#12 0x00007f58b398a6d0 in MessageList::Core::Model::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib64/libmessagelist.so.4
#13 0x00007f58ceacfa5f in QMetaObject::activate (sender=0xc313bd0, m=<value optimized out>, local_signal_index=<value optimized out>, 
    argv=0x7ffff2e4cff0) at kernel/qobject.cpp:3278
#14 0x00007f58ceb179ad in QAbstractItemModel::headerDataChanged (this=<value optimized out>, _t1=Qt::Horizontal, _t2=0, _t3=0)
    at .moc/release-shared/moc_qabstractitemmodel.cpp:155
#15 0x00007f58b39c748a in MessageList::StorageModel::Private::onSelectionChanged() () from /usr/lib64/libmessagelist.so.4
#16 0x00007f58b39c84d5 in MessageList::StorageModel::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib64/libmessagelist.so.4
#17 0x00007f58ceacfa5f in QMetaObject::activate (sender=0xaf93c0, m=<value optimized out>, local_signal_index=<value optimized out>, 
    argv=0x7ffff2e4d140) at kernel/qobject.cpp:3278
#18 0x00007f58ce3df3b7 in QItemSelectionModel::selectionChanged (this=<value optimized out>, _t1=<value optimized out>, 
    _t2=<value optimized out>) at .moc/release-shared/moc_qitemselectionmodel.cpp:152
#19 0x00007f58ce3e5b79 in QItemSelectionModel::emitSelectionChanged (this=0xaf93c0, newSelection=<value optimized out>, 
    oldSelection=<value optimized out>) at itemviews/qitemselectionmodel.cpp:1594
#20 0x00007f58ce3e636c in QItemSelectionModel::select (this=0xaf93c0, selection=<value optimized out>, command=...)
    at itemviews/qitemselectionmodel.cpp:1101
#21 0x00007f58b39c558a in MessageList::Pane::Private::onSelectionChanged(QItemSelection const&, QItemSelection const&) ()
   from /usr/lib64/libmessagelist.so.4
#22 0x00007f58b39c6487 in MessageList::Pane::qt_metacall(QMetaObject::Call, int, void**) () from /usr/lib64/libmessagelist.so.4
#23 0x00007f58ceacfa5f in QMetaObject::activate (sender=0xb0b1e0, m=<value optimized out>, local_signal_index=<value optimized out>, 
    argv=0x7ffff2e4d6a0) at kernel/qobject.cpp:3278
#24 0x00007f58ce3df3b7 in QItemSelectionModel::selectionChanged (this=<value optimized out>, _t1=<value optimized out>, 
    _t2=<value optimized out>) at .moc/release-shared/moc_qitemselectionmodel.cpp:152
#25 0x00007f58ce3e5b79 in QItemSelectionModel::emitSelectionChanged (this=0xb0b1e0, newSelection=<value optimized out>, 
    oldSelection=<value optimized out>) at itemviews/qitemselectionmodel.cpp:1594
#26 0x00007f58ce3e636c in QItemSelectionModel::select (this=0xb0b1e0, selection=<value optimized out>, command=...)
    at itemviews/qitemselectionmodel.cpp:1101
#27 0x00007f58ce3d54f4 in QTreeViewPrivate::select (this=0xd069b0, topIndex=<value optimized out>, bottomIndex=<value optimized out>, 
    command=...) at itemviews/qtreeview.cpp:3652
---Type <return> to continue, or q <return> to quit---
#28 0x00007f58ce3d6158 in QTreeView::setSelection (this=<value optimized out>, rect=<value optimized out>, command=...)
    at itemviews/qtreeview.cpp:2280
#29 0x00007f58ce38c5d1 in QAbstractItemView::mousePressEvent (this=0xd2da30, event=<value optimized out>)
    at itemviews/qabstractitemview.cpp:1674
#30 0x00007f58cded4f49 in QWidget::event (this=0xd2da30, event=0x7ffff2e4ed90) at kernel/qwidget.cpp:8255
#31 0x00007f58ce279a86 in QFrame::event (this=0xd2da30, e=0x7ffff2e4ed90) at widgets/qframe.cpp:557
#32 0x00007f58ce389ec3 in QAbstractItemView::viewportEvent (this=0xd2da30, event=0x7ffff2e4ed90) at itemviews/qabstractitemview.cpp:1628
#33 0x00007f58ce3cecc5 in QTreeView::viewportEvent (this=0xd2da30, event=0x7ffff2e4ed90) at itemviews/qtreeview.cpp:1256
#34 0x00007f58ceabb607 in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=<value optimized out>, receiver=0xd08850, 
    event=0x7ffff2e4ed90) at kernel/qcoreapplication.cpp:846
#35 0x00007f58cde83111 in QApplicationPrivate::notify_helper (this=0x63c150, receiver=0xd08850, e=0x7ffff2e4ed90)
    at kernel/qapplication.cpp:4458
#36 0x00007f58cde8bf7c in QApplication::notify (this=<value optimized out>, receiver=0xd08850, e=0x7ffff2e4ed90)
    at kernel/qapplication.cpp:4023
#37 0x00007f58cf501736 in KApplication::notify(QObject*, QEvent*) () from /usr/lib64/libkdeui.so.5
#38 0x00007f58ceabb47c in QCoreApplication::notifyInternal (this=0x7ffff2e4fac0, receiver=0xd08850, event=0x7ffff2e4ed90)
    at kernel/qcoreapplication.cpp:731
#39 0x00007f58cde84155 in sendEvent (receiver=0xd08850, event=0x7ffff2e4ed90, alienWidget=0xd08850, nativeWidget=0xc54f40, 
    buttonDown=0x7f58ce955198, lastMouseReceiver=..., spontaneous=true) at ../../src/corelib/kernel/qcoreapplication.h:215
#40 QApplicationPrivate::sendMouseEvent (receiver=0xd08850, event=0x7ffff2e4ed90, alienWidget=0xd08850, nativeWidget=0xc54f40, 
    buttonDown=0x7f58ce955198, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:3122
#41 0x00007f58cdf02b48 in QETWidget::translateMouseEvent (this=0xc54f40, event=<value optimized out>) at kernel/qapplication_x11.cpp:4461
#42 0x00007f58cdf01209 in QApplication::x11ProcessEvent (this=0x7ffff2e4fac0, event=0x7ffff2e4f6f0) at kernel/qapplication_x11.cpp:3587
#43 0x00007f58cdf28f12 in x11EventSourceDispatch (s=0x648bb0, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#44 0x00007f58c71a9bd3 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#45 0x00007f58c71aa3b0 in ?? () from /lib64/libglib-2.0.so.0
#46 0x00007f58c71aa650 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#47 0x00007f58ceae622f in QEventDispatcherGlib::processEvents (this=0x612790, flags=<value optimized out>)
    at kernel/qeventdispatcher_glib.cpp:422
#48 0x00007f58cdf28bae in QGuiEventDispatcherGlib::processEvents (this=<value optimized out>, flags=<value optimized out>)
    at kernel/qguieventdispatcher_glib.cpp:204
#49 0x00007f58ceaba8d2 in QEventLoop::processEvents (this=<value optimized out>, flags=...) at kernel/qeventloop.cpp:149
#50 0x00007f58ceabaae5 in QEventLoop::exec (this=0x7ffff2e4fa10, flags=...) at kernel/qeventloop.cpp:201
#51 0x00007f58ceabef2b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1008
#52 0x000000000040416f in _start ()


Reproducible: Sometimes

Steps to Reproduce:
Select a folder with a larger number of mails. Due to other bugs, the akonadi resources use huges amounts of CPU and memory.

Actual Results:  
UI freeze

Expected Results:  
no synchronous wait in the UI thread 

OS: Linux (x86_64) release 3.0.0-1-desktop
Compiler: gcc