unity-panel-service consumes 100% of CPU

[Steve Magoun]

unity-panel-service frequently gets into a tight loop and consumes 100% of the CPU. It's not always in this state, but often is. A side effect of this state is that indicators and menus can be very slow (~30sec) to open. The indicators/menus open quickly when u-p-s is not consuming lots of CPU. u-p-s can stay in this state for a couple minutes before returning to a quiescent state.

I don't know the exact steps to reproduce this behavior. It's a regression from 13.04.

Stack trace of u-p-s when it's consuming 100% of CPU:

(gdb) thread apply all bt

Thread 3 (Thread 0x7f5130b6e700 (LWP 2118)):
#0 0x00007f51387273dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1 0x00007f5138c66394 in g_main_context_poll (priority=2147483647, n_fds=3,
    fds=0x7f512c0010c0, timeout=-1, context=0x2498e40)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3999
#2 g_main_context_iterate (context=0x2498e40, block=block@entry=1,
    dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3700
#3 0x00007f5138c667fa in g_main_loop_run (loop=0x2498dd0)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3899
#4 0x00007f5139461646 in gdbus_shared_thread_func (user_data=0x2498e10)
    at /build/buildd/glib2.0-2.37.3/./gio/gdbusprivate.c:278
#5 0x00007f5138c8ac25 in g_thread_proxy (data=0x24454f0)
    at /build/buildd/glib2.0-2.37.3/./glib/gthread.c:798
#6 0x00007f5138a08f6e in start_thread (arg=0x7f5130b6e700)
    at pthread_create.c:311
#7 0x00007f5138733e2d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 2 (Thread 0x7f512bdf3700 (LWP 2164)):
#0 0x00007f51387273dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1 0x00007f5138c66394 in g_main_context_poll (priority=2147483647, n_fds=1,
---Type <return> to continue, or q <return> to quit---
    fds=0x7f51240010c0, timeout=-1, context=0x2442d60)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3999
#2 g_main_context_iterate (context=context@entry=0x2442d60,
    block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3700
#3 0x00007f5138c6649c in g_main_context_iteration (context=0x2442d60,
    may_block=1) at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3766
#4 0x00007f512bdfaa9d in ?? ()
   from /usr/lib/x86_64-linux-gnu/gio/modules/libdconfsettings.so
#5 0x00007f5138c8ac25 in g_thread_proxy (data=0x25b2f70)
    at /build/buildd/glib2.0-2.37.3/./glib/gthread.c:798
#6 0x00007f5138a08f6e in start_thread (arg=0x7f512bdf3700)
    at pthread_create.c:311
#7 0x00007f5138733e2d in clone ()
    at ../sysdeps/unix/sysv/linux/x86_64/clone.S:113

Thread 1 (Thread 0x7f513adff980 (LWP 2103)):
#0 0x00007f5138f3edd5 in handlers_find (instance=instance@entry=0x247eec0,
    mask=<optimized out>,
    mask@entry=(G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA),
    signal_id=signal_id@entry=0, detail=detail@entry=0,
    closure=closure@entry=0x0,
    func=func@entry=0x7f5139dc0460 <gtk_style_context_cascade_changed>,
---Type <return> to continue, or q <return> to quit---
    data=data@entry=0x518d3d0, one_and_only=one_and_only@entry=0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:555
#1 0x00007f5138f3f0df in signal_handlers_foreach_matched_R (
    instance=instance@entry=0x247eec0,
    mask=mask@entry=(G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA),
    signal_id=signal_id@entry=0, detail=detail@entry=0,
    closure=closure@entry=0x0,
    func=func@entry=0x7f5139dc0460 <gtk_style_context_cascade_changed>,
    data=data@entry=0x518d3d0,
    callback=callback@entry=0x7f5138f3e900 <g_signal_handler_disconnect>)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:2730
#2 0x00007f5138f47147 in g_signal_handlers_disconnect_matched (
    instance=0x247eec0,
    mask=mask@entry=(G_SIGNAL_MATCH_FUNC | G_SIGNAL_MATCH_DATA),
    signal_id=signal_id@entry=0, detail=detail@entry=0,
    closure=closure@entry=0x0,
    func=func@entry=0x7f5139dc0460 <gtk_style_context_cascade_changed>,
    data=data@entry=0x518d3d0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:2880
#3 0x00007f5139dc04dc in gtk_style_context_set_cascade (
    context=context@entry=0x518d3d0, cascade=cascade@entry=0x0)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkstylecontext.c:700
#4 0x00007f5139dc20b6 in gtk_style_context_finalize (object=0x518d3d0)
---Type <return> to continue, or q <return> to quit---
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkstylecontext.c:858
#5 0x00007f5138f32c9a in g_object_unref (_object=0x518d3d0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gobject.c:3194
#6 0x00007f5139e5ceda in gtk_widget_finalize (object=0x5451c00)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkwidget.c:10850
#7 0x00007f5138f32c9a in g_object_unref (_object=0x5451c00)
    at /build/buildd/glib2.0-2.37.3/./gobject/gobject.c:3194
#8 0x00007f5139cabf50 in gtk_container_destroy (widget=0x54ecb30)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkcontainer.c:1377
#9 0x00007f5138f2e268 in g_closure_invoke (closure=0x241e780,
    return_value=0x0, n_param_values=1, param_values=0x7fff50f0c9a0,
    invocation_hint=0x7fff50f0c940)
    at /build/buildd/glib2.0-2.37.3/./gobject/gclosure.c:777
#10 0x00007f5138f40a64 in signal_emit_unlocked_R (node=node@entry=0x2428450,
    detail=detail@entry=0, instance=instance@entry=0x54ecb30,
    emission_return=emission_return@entry=0x0,
    instance_and_params=instance_and_params@entry=0x7fff50f0c9a0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:3698
#11 0x00007f5138f488ba in g_signal_emit_valist (instance=<optimized out>,
    signal_id=<optimized out>, detail=<optimized out>,
    var_args=var_args@entry=0x7fff50f0cb28)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:3326
#12 0x00007f5138f48b92 in g_signal_emit (instance=instance@entry=0x54ecb30,
---Type <return> to continue, or q <return> to quit---
    signal_id=<optimized out>, detail=detail@entry=0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:3382
#13 0x00007f5139e6ac10 in gtk_widget_dispose (object=0x54ecb30)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkwidget.c:10771
#14 0x00007f5138f32c0c in g_object_unref (_object=0x54ecb30)
    at /build/buildd/glib2.0-2.37.3/./gobject/gobject.c:3157
#15 0x00007f5138f31344 in g_cclosure_marshal_VOID__OBJECTv (closure=0x243df00,
    return_value=<optimized out>, instance=<optimized out>,
    args=<optimized out>, marshal_data=0x7f5139d4a6f0 <gtk_menu_remove>,
    n_params=<optimized out>, param_types=0x243df30)
    at /build/buildd/glib2.0-2.37.3/./gobject/gmarshal.c:1316
#16 0x00007f5138f2e497 in _g_closure_invoke_va (closure=0x243df00,
    return_value=0x0, instance=0x568eb30, args=0x7fff50f0ce68, n_params=1,
    param_types=0x243df30)
    at /build/buildd/glib2.0-2.37.3/./gobject/gclosure.c:840
#17 0x00007f5138f482bc in g_signal_emit_valist (instance=0x568eb30,
    signal_id=<optimized out>, detail=<optimized out>,
    var_args=var_args@entry=0x7fff50f0ce68)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:3234
#18 0x00007f5138f48b92 in g_signal_emit (instance=<optimized out>,
    signal_id=<optimized out>, detail=detail@entry=0)
    at /build/buildd/glib2.0-2.37.3/./gobject/gsignal.c:3382
#19 0x00007f5139caa4e4 in gtk_container_remove (container=<optimized out>,
---Type <return> to continue, or q <return> to quit---
    widget=<optimized out>)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkcontainer.c:1546
#20 0x00007f5139d5d5ac in gtk_model_menu_binding_populate (
    binding=binding@entry=0x56b6240)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkmodelmenu.c:342
#21 0x00007f5139d5d640 in gtk_model_menu_binding_handle_changes (
    user_data=0x56b6240)
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkmodelmenu.c:366
#22 0x00007f513993ac48 in gdk_threads_dispatch (data=0xad58240)
    at /build/buildd/gtk+3.0-3.8.2/./gdk/gdk.c:788
#23 0x00007f5138c660a6 in g_main_dispatch (context=0x247d830)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3058
#24 g_main_context_dispatch (context=context@entry=0x247d830)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3634
#25 0x00007f5138c663f8 in g_main_context_iterate (context=0x247d830,
    block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3705
#26 0x00007f5138c667fa in g_main_loop_run (loop=0x25f9e00)
    at /build/buildd/glib2.0-2.37.3/./glib/gmain.c:3899
#27 0x00007f5139d3d365 in gtk_main ()
    at /build/buildd/gtk+3.0-3.8.2/./gtk/gtkmain.c:1156
#28 0x0000000000404c87 in main ()
(gdb)

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: unity-services 7.1.0+13.10.20130809.1-0ubuntu1
ProcVersionSignature: Ubuntu 3.10.0-6.17-generic 3.10.3
Uname: Linux 3.10.0-6-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12-0ubuntu3
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Mon Aug 12 14:13:56 2013
InstallationDate: Installed on 2010-09-17 (1060 days ago)
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Beta amd64 (20100901.1)
MarkForUpload: True
SourcePackage: unity
UpgradeStatus: Upgraded to saucy on 2013-08-07 (5 days ago)

[Christopher Townsend (townsend)]

Marking this as a duplicate to bug #1199877.