Thread 6 (Thread 0x7fffe5783700 (LWP 3990)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007fffdbe543b4 in WTF::TCMalloc_PageHeap::runScavengerThread(void*) () from /usr/lib64/qt4/libQtWebKit.so.4
#2  0x00007ffff538ad0c in start_thread (arg=0x7fffe5783700) at pthread_create.c:301
#3  0x00007ffff3c6dbed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 5 (Thread 0x7fffd4c0d700 (LWP 3991)):
#0  0x00007ffff3c64d13 in *__GI___poll (fds=<optimized out>, nfds=<optimized out>, timeout=<optimized out>) at ../sysdeps/unix/sysv/linux/poll.c:87
#1  0x00007fffef17dd93 in g_main_context_poll (n_fds=1, fds=0x1da3f60, timeout=-1, context=0x1ead430, priority=<optimized out>) at gmain.c:3402
#2  g_main_context_iterate (context=0x1ead430, block=1, dispatch=1, self=<optimized out>) at gmain.c:3084
#3  0x00007fffef17e261 in g_main_context_iteration (context=0x1ead430, may_block=1) at gmain.c:3152
#4  0x00007ffff5751c1f in QEventDispatcherGlib::processEvents (this=0x1eac240, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#5  0x00007ffff57215e2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#6  0x00007ffff572189d in QEventLoop::exec (this=0x7fffd4c0ce00, flags=...) at kernel/qeventloop.cpp:204
#7  0x00007ffff561d168 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:501
#8  0x00007ffff561f7eb in QThreadPrivate::start (arg=0x1eac590) at thread/qthread_unix.cpp:307
#9  0x00007ffff538ad0c in start_thread (arg=0x7fffd4c0d700) at pthread_create.c:301
#10 0x00007ffff3c6dbed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 4 (Thread 0x7fffd108d700 (LWP 3997)):
#0  syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:39
#1  0x00007ffff561ec43 in _q_futex (val2=0, addr2=0x0, timeout=0x0, val=2, op=0, addr=0x6e4340) at thread/qmutex_unix.cpp:99
#2  QMutexPrivate::wait (this=0x6e4340, timeout=<optimized out>) at thread/qmutex_unix.cpp:113
#3  0x00007ffff561af9d in QMutex::lock (this=<optimized out>) at thread/qmutex.cpp:164
#4  0x00007ffff7aace9c in net::DownloadThread::update (this=0x6e40b0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/downloadthread.cpp:51
#5  0x00007ffff7aad089 in net::NetworkThread::run (this=0x6e40b0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/networkthread.cpp:48
#6  0x00007ffff561f7eb in QThreadPrivate::start (arg=0x6e40b0) at thread/qthread_unix.cpp:307
#7  0x00007ffff538ad0c in start_thread (arg=0x7fffd108d700) at pthread_create.c:301
#8  0x00007ffff3c6dbed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 3 (Thread 0x7fffd088c700 (LWP 3998)):
#0  syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:39
#1  0x00007ffff561ec43 in _q_futex (val2=0, addr2=0x0, timeout=0x0, val=2, op=0, addr=0x7fffe154c690) at thread/qmutex_unix.cpp:99
#2  QMutexPrivate::wait (this=0x7fffe154c690, timeout=<optimized out>) at thread/qmutex_unix.cpp:113
#3  0x00007ffff561af9d in QMutex::lock (this=<optimized out>) at thread/qmutex.cpp:164
#4  0x00007ffff7add5e8 in lockInline (this=0x7fffe16bef40) at /usr/include/qt4/QtCore/qmutex.h:188
#5  QMutexLocker (m=0x7fffe16bef40, this=0x7fffd088bbd0) at /usr/include/qt4/QtCore/qmutex.h:109
#6  bt::HttpConnection::dataSent (this=0x7fffe16bef10) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/download/httpconnection.cpp:171
#7  0x00007ffff7ab1ffb in net::StreamSocket::write (this=0x7fffe16c7fc0, max=<optimized out>, now=<optimized out>) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/streamsocket.cpp:74
#8  0x00007ffff7aae09f in net::SocketGroup::processLimited (this=0x6e48b0, up=true, now=1339273162011, allowance=@0x7fffd088bd1c: 581) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/socketgroup.cpp:77
#9  0x00007ffff7aae34c in net::SocketGroup::process (this=0x6e48b0, up=<optimized out>, now=<optimized out>, global_allowance=@0x7fffd088bd1c: 581) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/socketgroup.cpp:188
#10 0x00007ffff7aad19d in net::NetworkThread::doGroupsLimited (this=0x6e45c0, num_ready=121, now=1339273162011, allowance=@0x7fffd088bd7c: 635) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/networkthread.cpp:111
#11 0x00007ffff7aad469 in net::NetworkThread::doGroups (this=0x6e45c0, num_ready=121, now=1339273162011, limit=<optimized out>) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/networkthread.cpp:190
#12 0x00007ffff7aac8df in net::UploadThread::update (this=0x6e45c0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/uploadthread.cpp:81
#13 0x00007ffff7aad089 in net::NetworkThread::run (this=0x6e45c0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/networkthread.cpp:48
#14 0x00007ffff561f7eb in QThreadPrivate::start (arg=0x6e45c0) at thread/qthread_unix.cpp:307
#15 0x00007ffff538ad0c in start_thread (arg=0x7fffd088c700) at pthread_create.c:301
#16 0x00007ffff3c6dbed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 2 (Thread 0x7fff8bfff700 (LWP 4014)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../nptl/sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:162
#1  0x00007ffff56206fb in wait (time=18446744073709551615, this=0x212a750) at thread/qwaitcondition_unix.cpp:86
#2  QWaitCondition::wait (this=<optimized out>, mutex=0x21098a0, time=18446744073709551615) at thread/qwaitcondition_unix.cpp:158
#3  0x00007ffff7aaf9d2 in net::ReverseResolverThread::run (this=0x2109890) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/reverseresolver.cpp:124
#4  0x00007ffff561f7eb in QThreadPrivate::start (arg=0x2109890) at thread/qthread_unix.cpp:307
#5  0x00007ffff538ad0c in start_thread (arg=0x7fff8bfff700) at pthread_create.c:301
#6  0x00007ffff3c6dbed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:115

Thread 1 (Thread 0x7ffff7fa8780 (LWP 3988)):
#0  syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:39
#1  0x00007ffff561ec43 in _q_futex (val2=0, addr2=0x0, timeout=0x0, val=2, op=0, addr=0x7fffe16c7640) at thread/qmutex_unix.cpp:99
#2  QMutexPrivate::wait (this=0x7fffe16c7640, timeout=<optimized out>) at thread/qmutex_unix.cpp:113
#3  0x00007ffff561af9d in QMutex::lock (this=<optimized out>) at thread/qmutex.cpp:164
#4  0x00007ffff7ab1c35 in net::TrafficShapedSocket::updateSpeeds (this=0x7fffe16c7fc0, now=1339273162011) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/net/trafficshapedsocket.cpp:99
#5  0x00007ffff7addf39 in bt::HttpConnection::getDownloadRate (this=0x7fffe16bef10) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/download/httpconnection.cpp:314
#6  0x00007ffff7acf8b4 in bt::WebSeed::getDownloadRate (this=<optimized out>) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/download/webseed.cpp:122
#7  0x00007ffff7ada679 in bt::Downloader::downloadRate (this=0x167edc0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/download/downloader.cpp:527
---Type <return> to continue, or q <return> to quit---
#8  0x00007ffff7aedbf2 in bt::TorrentControl::updateStatus (this=0x1676aa0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/torrent/torrentcontrol.cpp:990
#9  0x00007ffff7af7053 in bt::TorrentControl::update (this=0x1676aa0) at /var/tmp-disk/portage/net-libs/libktorrent-1.2.0/work/libktorrent-1.2.0/src/torrent/torrentcontrol.cpp:219
#10 0x000000000042edd3 in kt::Core::update (this=0x71d440) at /var/tmp-disk/portage/net-p2p/ktorrent-4.2.0/work/ktorrent-4.2.0/ktorrent/core.cpp:1046
#11 0x0000000000435e3a in kt::Core::qt_static_metacall (_o=<optimized out>, _c=<optimized out>, _id=<optimized out>, _a=<optimized out>) at /var/tmp-disk/portage/net-p2p/ktorrent-4.2.0/work/ktorrent-4.2.0_build/ktorrent/core.moc:141
#12 0x00007ffff57381ea in QMetaObject::activate (sender=0x71d468, m=<optimized out>, local_signal_index=<optimized out>, argv=0x0) at kernel/qobject.cpp:3547
#13 0x00007ffff5737359 in QObject::event (this=0x71d468, e=<optimized out>) at kernel/qobject.cpp:1157
#14 0x00007ffff489bd24 in QApplicationPrivate::notify_helper (this=0x732330, receiver=0x71d468, e=0x7fffffffc9f0) at kernel/qapplication.cpp:4551
#15 0x00007ffff48a089f in QApplication::notify (this=<optimized out>, receiver=0x71d468, e=0x7fffffffc9f0) at kernel/qapplication.cpp:4412
#16 0x000000000043c541 in kt::App::notify (this=<optimized out>, receiver=<optimized out>, event=<optimized out>) at /var/tmp-disk/portage/net-p2p/ktorrent-4.2.0/work/ktorrent-4.2.0/ktorrent/app.cpp:99
#17 0x00007ffff572288c in QCoreApplication::notifyInternal (this=0x7fffffffcd40, receiver=0x71d468, event=0x7fffffffc9f0) at kernel/qcoreapplication.cpp:915
#18 0x00007ffff57546de in sendEvent (event=0x7fffffffc9f0, receiver=<optimized out>) at kernel/qcoreapplication.h:231
#19 QTimerInfoList::activateTimers (this=0x70d140) at kernel/qeventdispatcher_unix.cpp:611
#20 0x00007ffff57514cd in timerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:186
#21 0x00007ffff57514f1 in idleTimerSourceDispatch (source=<optimized out>) at kernel/qeventdispatcher_glib.cpp:233
#22 0x00007fffef17d87f in g_main_dispatch (context=0x70a9a0) at gmain.c:2441
#23 g_main_context_dispatch (context=0x70a9a0) at gmain.c:3011
#24 0x00007fffef17e088 in g_main_context_iterate (context=0x70a9a0, block=1, dispatch=1, self=<optimized out>) at gmain.c:3089
#25 0x00007fffef17e261 in g_main_context_iteration (context=0x70a9a0, may_block=1) at gmain.c:3152
#26 0x00007ffff5751c1f in QEventDispatcherGlib::processEvents (this=0x74e160, flags=...) at kernel/qeventdispatcher_glib.cpp:424
#27 0x00007ffff494133e in QGuiEventDispatcherGlib::processEvents (this=<optimized out>, flags=...) at kernel/qguieventdispatcher_glib.cpp:204
#28 0x00007ffff57215e2 in QEventLoop::processEvents (this=<optimized out>, flags=...) at kernel/qeventloop.cpp:149
#29 0x00007ffff572189d in QEventLoop::exec (this=0x7fffffffcca0, flags=...) at kernel/qeventloop.cpp:204
#30 0x00007ffff572632b in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1187
#31 0x000000000042c3f5 in main (argc=1, argv=0x7fffffffdbb8) at /var/tmp-disk/portage/net-p2p/ktorrent-4.2.0/work/ktorrent-4.2.0/ktorrent/main.cpp:177

Reproducible: Always

Steps to Reproduce:
Append after 4~ hours. It freeze all during the most time (Gui thread not totally freezed).