Bug 345901 - plasmashell hangs every few minutes without apparent reason.
Summary: plasmashell hangs every few minutes without apparent reason.
Status: RESOLVED FIXED
Alias: None
Product: plasmashell
Classification: Plasma
Component: general (show other bugs)
Version: master
Platform: Arch Linux Linux
: NOR grave
Target Milestone: 1.0
Assignee: David Edmundson
URL:
Keywords:
: 346963 (view as bug list)
Depends on:
Blocks:
 
Reported: 2015-04-05 20:28 UTC by dmidge
Modified: 2015-09-26 15:24 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed In:

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Description dmidge 2015-04-05 20:28:43 UTC 
Every 3 to 10 minutes, plasmashell hangs completely without any apparent reasons. That means that I can't access the taskbar, I can't use kickoff, the clock is frozen (very useful to find the moment of the crash by the way), I can't access the desktop (so I can't add any shortcut or anything).

But, the rest of the computer is still responsive. I can still change of desktop or window thanks to the keyboard shortcuts, I can launch a new program through an already open konsole, the other applications remain responsive, etc.

Reproducible: Always

Steps to Reproduce:
1. Launch plasma by logging in sddm.
2. Wait around 3 to 10 minutes (or use your computer as usual). There is no apparent connection or effect when another application is launched when plasmashell is still responsive.

Actual Results:  
Plasmashell hangs indefinitely, until I kill it and lauch it again through the konsole. Then, it is working again for another 3 to 10 minutes, until it crashes again.
At some point, repeating the killing/re-executing operation make my computer crash completely, but it could be because of another problem (some memory leaks coming from the killing step for example).


*****$:konsole --version
Qt: 5.4.1
KDE Frameworks: 5.8.0
Konsole: 3.0.1

Also, nothing useful comes up in ~/.xsession-error, /var/log/Xorg.0.log or dmesg.

I got the stacktrace, and it seems that there is a problem in the libc.so library, making the main thread waiting for that threads to finish, to be able to get a lock or semaphore. By the way, I ran it twice: it crashes exactly the same way, with the same calls, and with 27 threads. The only differences are the LWP numbers according to a diff). So, there is the stacktrace you are waiting for:

Thread 27 (Thread 0x7fffe32ac700 (LWP 2339)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007ffff6a439f2 in ?? () from /usr/lib/libxcb.so.1
No symbol table info available.
#2  0x00007ffff6a4556f in xcb_wait_for_event () from /usr/lib/libxcb.so.1
No symbol table info available.
#3  0x00007fffe4bc9399 in ?? () from /usr/lib/qt/plugins/platforms/libqxcb.so
No symbol table info available.
#4  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#6  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 26 (Thread 0x7fffcb7ff700 (LWP 2342)):
#0  0x00007ffff2bad1b3 in select () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007ffff339fa61 in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#2  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#3  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#4  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 25 (Thread 0x7fffcaffe700 (LWP 2345)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 24 (Thread 0x7fffa6ffe700 (LWP 2352)):
#0  0x00007ffff21ae9af in pthread_cond_wait@@GLIBC_2.3.2 () from /usr/lib/libpthread.so.0
No symbol table info available.
#1  0x00007ffff786d634 in ?? () from /usr/lib/libQt5Script.so.5
No symbol table info available.
#2  0x00007ffff786d679 in ?? () from /usr/lib/libQt5Script.so.5
No symbol table info available.
#3  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#4  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 23 (Thread 0x7fffa67fd700 (LWP 2353)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 22 (Thread 0x7fff176a1700 (LWP 2356)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5d3dba6 in ?? () from /usr/lib/libQt5Quick.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 21 (Thread 0x7fff15da8700 (LWP 2357)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 20 (Thread 0x7fff0e8e5700 (LWP 2358)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 19 (Thread 0x7fff03fff700 (LWP 2360)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 18 (Thread 0x7fff02ffe700 (LWP 2361)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 17 (Thread 0x7fff01ffd700 (LWP 2362)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 16 (Thread 0x7fff00ffc700 (LWP 2363)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 15 (Thread 0x7ffeef7ff700 (LWP 2364)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 14 (Thread 0x7ffee3fff700 (LWP 2366)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff346508c in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 13 (Thread 0x7ffee2ffe700 (LWP 2367)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 12 (Thread 0x7ffeee7fe700 (LWP 2365)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 11 (Thread 0x7fff0d7e2700 (LWP 2359)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 10 (Thread 0x7fffb97fd700 (LWP 2350)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 9 (Thread 0x7fffba7fe700 (LWP 2349)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 8 (Thread 0x7fffbb7ff700 (LWP 2348)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 7 (Thread 0x7fffc8ffc700 (LWP 2347)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 6 (Thread 0x7fffc9ffd700 (LWP 2346)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 5 (Thread 0x7fffa5086700 (LWP 2354)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 4 (Thread 0x7fffa7fff700 (LWP 2351)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 3 (Thread 0x7fffd0da1700 (LWP 2341)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 2 (Thread 0x7fffe0ece700 (LWP 2340)):
#0  0x00007ffff2bab4ed in poll () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007fffef6e89a4 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#2  0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#3  0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#5  0x00007ffff321c5d4 in QThread::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#6  0x00007ffff5ae5835 in ?? () from /usr/lib/libQt5Qml.so.5
No symbol table info available.
#7  0x00007ffff322155e in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#8  0x00007ffff21a9374 in start_thread () from /usr/lib/libpthread.so.0
No symbol table info available.
#9  0x00007ffff2bb427d in clone () from /usr/lib/libc.so.6
No symbol table info available.

Thread 1 (Thread 0x7fffe4de1780 (LWP 2335)):
#0  0x00007ffff2b83ead in nanosleep () from /usr/lib/libc.so.6
No symbol table info available.
#1  0x00007ffff32d695d in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#2  0x00007ffff3220948 in QThread::msleep(unsigned long) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#3  0x00007ffff3332aa0 in QLockFile::tryLock(int) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#4  0x00007ffff4488239 in ?? () from /usr/lib/libKF5ConfigCore.so.5
No symbol table info available.
#5  0x00007ffff4468c56 in KConfig::sync() () from /usr/lib/libKF5ConfigCore.so.5
No symbol table info available.
#6  0x00007ffff6809d83 in ?? () from /usr/lib/libKF5Plasma.so.5
No symbol table info available.
#7  0x00007ffff6812565 in ?? () from /usr/lib/libKF5Plasma.so.5
No symbol table info available.
#8  0x00007ffff343d309 in QMetaObject::activate(QObject*, int, int, void**) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#9  0x00007ffff344b108 in QTimer::timerEvent(QTimerEvent*) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#10 0x00007ffff343e023 in QObject::event(QEvent*) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#11 0x00007ffff3f04acc in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
No symbol table info available.
#12 0x00007ffff3f09f10 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/libQt5Widgets.so.5
No symbol table info available.
#13 0x00007ffff340cd1b in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#14 0x00007ffff3463f6d in QTimerInfoList::activateTimers() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#15 0x00007ffff34643e9 in ?? () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#16 0x00007fffef6e871d in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#17 0x00007fffef6e8a08 in ?? () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#18 0x00007fffef6e8abc in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
No symbol table info available.
#19 0x00007ffff3465077 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#20 0x00007ffff340a7b2 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#21 0x00007ffff341218c in QCoreApplication::exec() () from /usr/lib/libQt5Core.so.5
No symbol table info available.
#22 0x000000000042e78b in main ()
No symbol table info available.


It doesn't seem to be a driver problem, since it was fine for 4 years, I didn't receive any updates recently, and the applications graphical interface are still responsive.

You can ask questions, I will try answer it as good as I can. Any idea so far?
Comment 1 David Edmundson 2015-04-06 01:21:38 UTC 
Look in .cache for a file ending in .lock.
After 3 minutes plasma saves any pending cached images to this file, but here it's blocking because it thinks someone else has that file open.

Hopefully this lock file shouldn't left anymore after a change I made around January.
Comment 2 dmidge 2015-04-06 05:00:39 UTC 
And you are right! You nailed the problem! Good news then! By removing the file ".cache/plasma-svgelements-default_v0.9.7.lock", everything works perfectly again! So at least, I have a better temporary solution than just kill and launch again.

But isn't KF 5.8.0 supposed to be the last version? Besides, when I execute this command:
xxxxx$ plasmashell --version
plasmashell 5.2.2
If I am right, it is the last version, shipped at the end of march. That means that another similar bug occurs with this version again, unfortunately. Unless your patch hasn't been applied yet, of course.

But it is on the good path, at least!
Comment 3 dmidge 2015-04-06 14:19:24 UTC 
I had few hangs since I deleted the lock file, which means the problem is not solved yet. To delete the file once is not enough: time to time, I have to repeat the operation when I am using the computer. But at least, you have spotted the problem!
So don't close the bug file now, I still need a patch. Don't hesitate to ask if you have more questions.
Comment 4 David Edmundson 2015-04-06 14:20:40 UTC 
OK, thanks for reporting back.
Comment 5 David Edmundson 2015-04-06 16:15:35 UTC 
OK, next time can you attach the file.
also run ls -l on the file so I can see the timestamp of it.
Comment 6 dmidge 2015-04-06 16:30:03 UTC 
It is a completely blank file. (Bugzilla don't even want to attach it because of that).

There is the ls -l:
me$ ls -l .cache/plasma-svgelements-default_v0.9.7.lock
-rw-r--r-- 1 me users 0  6 avril 09:23 .cache/plasma-svgelements-default_v0.9.7.lock
Comment 7 David Edmundson 2015-04-06 16:50:38 UTC 
Blah, there's a bug in QLockFile

bool QLockFilePrivate::isApparentlyStale() const
{
    if (!getLockInfo(&pid, &hostname, &appname))
        return false;

if it can't read the lock file information, it assumes it's not stale at which point we block forever, waiting for the lock to become stale which will never happen.

Doesn't explain why Qt is writing empty lock files, but that's another story.
Comment 8 dmidge 2015-04-06 19:35:36 UTC 
Arff, bad luck! That means that we should notify this problem to the Qt team then. I am not sure that I will be able to give as much as you about that bug to the Qt team. Maybe can you contact them and explain them the issue, so they can fix it on their own.

But if I get what you're saying, having an empty lock should never happen. Maybe it is possible to fix this side of the problem? At least if you (or the KDE team) can fix it: I won't be able to dive in the code myself in the following days.
Hopefully, the freeze caused by blank lock file issue will be fixed soon by the Qt team.
Comment 9 dmidge 2015-04-06 20:36:21 UTC 
I just want to add something: once the lock file has been removed manually, the system becomes more reliable. Meaning that, for the last 70 minutes, I didn't have any freeze, which was not possible before. But yesterday, I experienced few crashes, even after I removed the lock file, but not today.
By the way, I gave you the information on the lock file when I was running Gnome, so this lock was there when I killed plasmashell and then rebooted through tty. I don't know if it changes anything, but I hope not. And since it didn't crashed again since I deleted it manually, I can't check the information I got through Gnome.
Comment 10 dmidge 2015-04-19 19:38:35 UTC 
I should add something. I had another unexpected problem that prevented me to reach the KDE desktop (impossible to complete the KDE interface boot part). The solution was also to remove the  *.lock files. The symptoms and everything were very similar to what is described there: https://bbs.archlinux.org/viewtopic.php?id=195729. I didn't checked if the lock files were empty or not, but the same operation (deleting every *.lock) solved my problem. That means the Qt lock file problem is a bigger issue than expected! I think a major fix is needed soon! I don't know if you managed to give this information to the concerned team though.
Comment 11 dmidge 2015-04-19 19:48:54 UTC 
In the meantime, I have a question. Why are the lock files in the .config/ folder. Shouldn't they be in the cache folder? By definition, they are temporary files, that don't help to configure the KDE interface. Besides, the common procedure, when KDE fails to start, is to clean the /tmp, /var/tmp and .cache/. Nothing to do with .config/, so why not keeping it that way? Or maybe it could be a good idea to precise that every lock files should be deleted in the "troubleshooting KDE" documentation... Your call! But for sure, it would have saved me a lot of time (like a lot of fellows that are stuck on Internet) to have that step mentioned in the documentation.
Comment 12 David Edmundson 2015-04-28 16:51:25 UTC 
Wheee: https://codereview.qt-project.org/#/c/110346/

All fixed in Qt \o/
Comment 13 Yichao Yu 2015-05-01 12:51:08 UTC 
*** Bug 346963 has been marked as a duplicate of this bug. ***
Comment 14 dmidge 2015-05-09 19:05:13 UTC 
Thanks! Excellent news! :o)