> 2012/11/13 Alexander Liebendorfer <alex.liebendorf@gmail.com>:
> > https://sourceforge.net/apps/phpbb/lmms/viewtopic.php?f=7&t=689&start=0
>
> Which Qt version is this? Just asking because it looks like a Qt bug -
> from what I can see from the backtrace. Is anyone able to reproduce
> the issue? Maybe the guy can post the MMP file somewhere?
>
> Toby


Yes i can reproduce this same crash on ubuntu and the very latest git pull as
from a few days ago, lmms was working fine until a few days ago, so i believe
that it is a very recent commit causing this issue and not Qt as i checked my
package install/update history and i havnt had a qt update for some time.

i will paste my gdb output here as i think attachments dont
get through the mailing list filter.

( gdb output below )

Reading symbols from /home/ubu/lmms/target/bin/lmms...done.
(gdb) r
Starting program: /home/ubu/lmms/target/bin/lmms
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
[New Thread 0xb396eb40 (LWP 8920)]
[New Thread 0xb2fffb40 (LWP 8921)]
[New Thread 0xb25ffb40 (LWP 8922)]
[New Thread 0xb0c83b40 (LWP 8923)]
[Thread 0xb25ffb40 (LWP 8922) exited]
no more csLADSPA plugins
[New Thread 0xb25ffb40 (LWP 8924)]
[New Thread 0xae85ab40 (LWP 8925)]
[New Thread 0xa504db40 (LWP 8928)]
[New Thread 0xa484cb40 (LWP 8929)]
[New Thread 0xa36ecb40 (LWP 8933)]
[New Thread 0x9d4b1b40 (LWP 8934)]
[Thread 0xa504db40 (LWP 8928) exited]
[Thread 0xa484cb40 (LWP 8929) exited]
[New Thread 0xa484cb40 (LWP 8935)]
[New Thread 0xa504db40 (LWP 8936)]
[New Thread 0x9cb9bb40 (LWP 8937)]
[Thread 0xa504db40 (LWP 8936) exited]
[Thread 0x9cb9bb40 (LWP 8937) exited]
[Thread 0xb25ffb40 (LWP 8924) exited]
[New Thread 0xb25ffb40 (LWP 8938)]
[New Thread 0x9cb9bb40 (LWP 8939)]
[New Thread 0xa504db40 (LWP 8940)]
[Thread 0xa484cb40 (LWP 8935) exited]
[Thread 0x9cb9bb40 (LWP 8939) exited]
[Thread 0xa504db40 (LWP 8940) exited]

Program received signal SIGSEGV, Segmentation fault.
0x080fa12a in mixer::startProcessing (this=0x83a4388, _needs_fifo=false)
    at /home/ubu/lmms/src/core/mixer.cpp:451
451        m_audioDev->startProcessing();
(gdb) thread apply all backtrace

Thread 15 (Thread 0xb25ffb40 (LWP 8938)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb6a135f0 in __GI___poll (fds=0xb1c14858, nfds=2, timeout=9)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0xb6fd64c6 in ?? () from /usr/lib/i386-linux-gnu/libpulse.so.0
#3  0xb6fc475a in pa_mainloop_poll ()
   from /usr/lib/i386-linux-gnu/libpulse.so.0
#4  0xb6fc4fb7 in pa_mainloop_iterate ()
   from /usr/lib/i386-linux-gnu/libpulse.so.0
#5  0xb6fc5094 in pa_mainloop_run () from /usr/lib/i386-linux-gnu/libpulse.so.0
#6  0xb6fd644e in ?? () from /usr/lib/i386-linux-gnu/libpulse.so.0
#7  0xb641a246 in ?? () from /usr/lib/i386-linux-gnu/libpulsecommon-1.1.so
#8  0xb7fa2d4c in start_thread (arg=0xb25ffb40) at pthread_create.c:308
#9  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 11 (Thread 0x9d4b1b40 (LWP 8934)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb6a135f0 in __GI___poll (fds=0xb2606f30, nfds=2, timeout=-1)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0xb6841a7b in g_poll () from /lib/i386-linux-gnu/libglib-2.0.so.0
#3  0xb68340ae in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#4  0xb6834201 in g_main_context_iteration ()
---Type <return> to continue, or q <return> to quit---
   from /lib/i386-linux-gnu/libglib-2.0.so.0
#5  0xb735a887 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#6  0xb732650d in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#7  0xb73267a9 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#8  0xb720f94c in QThread::exec() ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#9  0xb7303b5d in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0xb7212de0 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#11 0xb7fa2d4c in start_thread (arg=0x9d4b1b40) at pthread_create.c:308
#12 0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 10 (Thread 0xa36ecb40 (LWP 8933)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb7fa696b in pthread_cond_wait@@GLIBC_2.3.2 ()
    at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_wait.S:169
#2  0xb7213350 in QWaitCondition::wait(QMutex*, unsigned long) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#3  0xb7b95fa3 in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#4  0xb7212de0 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
---Type <return> to continue, or q <return> to quit---
#5  0xb7fa2d4c in start_thread (arg=0xa36ecb40) at pthread_create.c:308
#6  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 7 (Thread 0xae85ab40 (LWP 8925)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb6a135f0 in __GI___poll (fds=0xb2602318, nfds=2, timeout=250)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0x0810c544 in MidiAlsaSeq::run (this=0x85053e8)
    at /home/ubu/lmms/src/core/midi/MidiAlsaSeq.cpp:453
#3  0xb7212de0 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#4  0xb7fa2d4c in start_thread (arg=0xae85ab40) at pthread_create.c:308
#5  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 5 (Thread 0xb0c83b40 (LWP 8923)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb7fa696b in pthread_cond_wait@@GLIBC_2.3.2 ()
    at ../nptl/sysdeps/unix/sysv/linux/i386/i686/../i486/pthread_cond_wait.S:169
#2  0xb7213350 in QWaitCondition::wait(QMutex*, unsigned long) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#3  0x080fc927 in MixerWorkerThread::run (this=0x83d0208)
    at /home/ubu/lmms/src/core/mixer.cpp:187
#4  0xb7212de0 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
---Type <return> to continue, or q <return> to quit---
#5  0xb7fa2d4c in start_thread (arg=0xb0c83b40) at pthread_create.c:308
#6  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 3 (Thread 0xb2fffb40 (LWP 8921)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb6a135f0 in __GI___poll (fds=0xb2602298, nfds=3, timeout=-1)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0xb6841a7b in g_poll () from /lib/i386-linux-gnu/libglib-2.0.so.0
#3  0xb68340ae in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#4  0xb683456b in g_main_loop_run () from /lib/i386-linux-gnu/libglib-2.0.so.0
#5  0xb47fa1ba in ?? () from /usr/lib/i386-linux-gnu/libgio-2.0.so.0
#6  0xb68576b3 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#7  0xb7fa2d4c in start_thread (arg=0xb2fffb40) at pthread_create.c:308
#8  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 2 (Thread 0xb396eb40 (LWP 8920)):
#0  0xb7fdd424 in __kernel_vsyscall ()
#1  0xb6a135f0 in __GI___poll (fds=0xb3000c78, nfds=1, timeout=-1)
    at ../sysdeps/unix/sysv/linux/poll.c:87
#2  0xb6841a7b in g_poll () from /lib/i386-linux-gnu/libglib-2.0.so.0
#3  0xb68340ae in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#4  0xb683456b in g_main_loop_run () from /lib/i386-linux-gnu/libglib-2.0.so.0
#5  0xb397a134 in ?? ()
---Type <return> to continue, or q <return> to quit---
   from /usr/lib/i386-linux-gnu/gio/modules/libdconfsettings.so
#6  0xb68576b3 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#7  0xb7fa2d4c in start_thread (arg=0xb396eb40) at pthread_create.c:308
#8  0xb6a21d3e in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:130

Thread 1 (Thread 0xb6089740 (LWP 8917)):
#0  0x080fa12a in mixer::startProcessing (this=0x83a4388, _needs_fifo=false)
    at /home/ubu/lmms/src/core/mixer.cpp:451
#1  0x080fa3bd in mixer::setAudioDevice (this=0x83a4388, _dev=0x8e96ba0,
    _qs=..., _needs_fifo=false) at /home/ubu/lmms/src/core/mixer.cpp:879
#2  0x08115c64 in ProjectRenderer::startProcessing (this=0x8e82470)
    at /home/ubu/lmms/src/core/ProjectRenderer.cpp:136
#3  0x0818d59b in exportProjectDialog::render (this=0xbfffe500,
    renderer=0x8e82470) at /home/ubu/lmms/src/gui/export_project_dialog.cpp:255
#4  0x0818e05f in exportProjectDialog::pop_render (this=0xbfffe500)
    at /home/ubu/lmms/src/gui/export_project_dialog.cpp:167
#5  0x0818ee30 in exportProjectDialog::accept (this=0xbfffe500)
    at /home/ubu/lmms/src/gui/export_project_dialog.cpp:113
#6  0x0818ec53 in qt_static_metacall (_a=0x8e665c8, _id=6, _o=0xbfffe500,
    _c=<optimised out>)
    at /home/ubu/lmms/build/include/moc_export_project_dialog.cxx:66
#7  exportProjectDialog::qt_static_metacall (_o=0xbfffe500,
    _c=QMetaObject::InvokeMetaMethod, _id=6, _a=0x8e665c8)
---Type <return> to continue, or q <return> to quit---
    at /home/ubu/lmms/build/include/moc_export_project_dialog.cxx:53
#8  0xb7339c01 in QMetaCallEvent::placeMetaCall(QObject*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#9  0xb7342c7b in QObject::event(QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#10 0xb765de62 in QWidget::event(QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#11 0xb7603ed4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#12 0xb76093a2 in QApplication::notify(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#13 0xb732797e in QCoreApplication::notifyInternal(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#14 0xb732bad8 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#15 0xb732be0c in QCoreApplication::sendPostedEvents(QObject*, int) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#16 0xb735a494 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#17 0xb6833d86 in g_main_context_dispatch ()
   from /lib/i386-linux-gnu/libglib-2.0.so.0
#18 0xb6834125 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#19 0xb6834201 in g_main_context_iteration ()
   from /lib/i386-linux-gnu/libglib-2.0.so.0
---Type <return> to continue, or q <return> to quit---
#20 0xb735a887 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#21 0xb76bcaaa in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#22 0xb732650d in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#23 0xb73267a9 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#24 0xb7b560d9 in QDialog::exec() () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#25 0x08100d6e in song::exportProject (this=0x83d4450, multiExport=false)
    at /home/ubu/lmms/src/core/song.cpp:1201
#26 0x08100e0f in ~QString (this=0x0, __in_chrg=<optimised out>)
    at /usr/include/qt4/QtCore/qstring.h:880
#27 song::exportProject (this=0x83d4450, multiExport=false)
    at /home/ubu/lmms/src/core/song.cpp:1151
#28 0x08103230 in qt_static_metacall (_a=0xbfffe788, _id=16, _o=0x83d4450,
    _c=<optimised out>) at /home/ubu/lmms/build/include/moc_song.cxx:115
#29 song::qt_static_metacall (_o=0x83d4450, _c=QMetaObject::InvokeMetaMethod,
    _id=16, _a=0xbfffe788) at /home/ubu/lmms/build/include/moc_song.cxx:93
#30 0xb733e6b1 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#31 0xb75fc9bd in QAction::triggered(bool) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#32 0xb75fcc5b in QAction::activate(QAction::ActionEvent) ()
---Type <return> to continue, or q <return> to quit---
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#33 0xb75fcfb8 in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#34 0xb7339c01 in QMetaCallEvent::placeMetaCall(QObject*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#35 0xb7342c7b in QObject::event(QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#36 0xb75fcd31 in QAction::event(QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#37 0xb7603ed4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#38 0xb760930d in QApplication::notify(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtGui.so.4
#39 0xb732797e in QCoreApplication::notifyInternal(QObject*, QEvent*) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#40 0xb732bad8 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#41 0xb732be0c in QCoreApplication::sendPostedEvents(QObject*, int) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#42 0xb735a494 in ?? () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#43 0xb6833d86 in g_main_context_dispatch ()
   from /lib/i386-linux-gnu/libglib-2.0.so.0
#44 0xb6834125 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#45 0xb6834201 in g_main_context_iteration ()
---Type <return> to continue, or q <return> to quit---
   from /lib/i386-linux-gnu/libglib-2.0.so.0
#46 0xb735a887 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#47 0xb76bcaaa in ?? () from /usr/lib/i386-linux-gnu/libQtGui.so.4
#48 0xb732650d in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/i386-linux-gnu/libQtCore.so.4
#49 0xb73267a9 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#50 0xb732beba in QCoreApplication::exec() ()
   from /usr/lib/i386-linux-gnu/libQtCore.so.4
#51 0x080ad9c4 in main (argc=139537392, argv=0x87f9750)
    at /home/ubu/lmms/src/core/main.cpp:509
(gdb)

hope this helps and if any more testing needs done don't hesitate to ask,

thanks Mikobuntu ;)