The gstack tool attaches to the process with the given PID and prints a stack trace with the last few calls of all the threads in it:
marc:~> gstack 28534
Thread 4 (Thread 0x7f6a2cddf700 (LWP 28537)):
#0 0x00007f6a54a75c8d in poll () from /lib64/libc.so.6
#1 0x00007f6a4ed7db34 in g_main_context_iterate.isra () from /lib64/libglib2.0.so.0
#2 0x00007f6a4ed7dc4c in g_main_context_iteration () from /lib64/libglib2.0.so.0
#3 0x00007f6a55bba57e in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#4 0x00007f6a55b89d81 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /lib64/libQtCore.so.4
#5 0x00007f6a55b8a0e5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#6 0x00007f6a55a7ebb9 in QThread::exec() () from /lib64/libQtCore.so.4
#7 0x00007f6a55b6a6e3 in QInotifyFileSystemWatcherEngine::run() () from /lib64/libQtCore.so.4
#8 0x00007f6a55a8141f in QThreadPrivate::start(void*) () from /lib64/libQtCore.so.4
#9 0x00007f6a557f052a in start_thread () from /lib64/libpthread.so.0
#10 0x00007f6a54a8122d in clone () from /lib64/libc.so.6
Thread 3 (Thread 0x7f6a27fff700 (LWP 28538)):
#0 0x00007f6a54a75c8d in poll () from /lib64/libc.so.6
#1 0x00007f6a4ed7db34 in g_main_context_iterate.isra () from /lib64/libglib2.0.so.0
#2 0x00007f6a4ed7dc4c in g_main_context_iteration () from /lib64/libglib2.0.so.0
#3 0x00007f6a55bba55e in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#4 0x00007f6a55b89d81 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /lib64/libQtCore.so.4
#5 0x00007f6a55b8a0e5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#6 0x00007f6a55a7ebb9 in QThread::exec() () from /lib64/libQtCore.so.4
#7 0x00007f6a55a8141f in QThreadPrivate::start(void*) () from /lib64/libQtCore.so.4
#8 0x00007f6a557f052a in start_thread () from /lib64/libpthread.so.0
#9 0x00007f6a54a8122d in clone () from /lib64/libc.so.6
Thread 2 (Thread 0x7f6a277fe700 (LWP 28539)):
#0 0x00007f6a54a75c8d in poll () from /lib64/libc.so.6
#1 0x00007f6a55bb7630 in qt_safe_poll(pollfd*, int, int, bool) () from /lib64/libQtCore.so.4
#2 0x00007f6a55b66e88 in QProcessManager::run() () from /lib64/libQtCore.so.4
#3 0x00007f6a55a8141f in QThreadPrivate::start(void*) () from /lib64/libQtCore.so.4
#4 0x00007f6a557f052a in start_thread () from /lib64/libpthread.so.0
#5 0x00007f6a54a8122d in clone () from /lib64/libc.so.6
Thread 1 (Thread 0x7f6a5a9ab900 (LWP 28534)):
#0 0x00007f6a54a75c8d in poll () from /lib64/libc.so.6
#1 0x00007f6a4ed7db34 in g_main_context_iterate.isra () from /lib64/libglib2.0.so.0
#2 0x00007f6a4ed7dc4c in g_main_context_iteration () from /lib64/libglib2.0.so.0
#3 0x00007f6a55bba55e in
QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#4 0x00007f6a56ac2176 in
QGuiEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtGui.so.4
#5 0x00007f6a55b89d81 in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) ()
from /lib64/libQtCore.so.4
#6 0x00007f6a55b8a0e5 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from
/lib64/libQtCore.so.4
#7 0x00007f6a55b8f7c9 in QCoreApplication::exec() () from /lib64/libQtCore.so.4
#8 0x00007f6a5a5cdbee in kdemain () from /lib64/libkdeinit4_dolphin.so
#9 0x00007f6a549a0fe0 in __libc_start_main () from /lib64/libc.so.6
#10 0x00000000004008de in _start ()