Bug 157891 – [GTK] Scrollbars plague console output with "g_object_unref: assertion 'object->ref_count > 0' failed" warnings with GTK < 3.20

• Status: RESOLVED
• Resolution: WONTFIX
• Component: WebKitGTK

[Jiří Janoušek]

Hello, I'm backporting WebKitGTK+ 2.12.2 to Debian Jessie and Ubuntu 14.04 for users of my webkitgtk-based app. It compiles fine, but hovering over scrollbars really plagues console output with "g_object_unref: assertion 'object->ref_count > 0' failed" warnings with GTK+ 3.14.5 and 3.10.8 respectively. Looking at the code of Source/WebCore/platform/gtk/ScrollbarThemeGtk.cpp, this bug probably occurs in a code branch specific to GTK+ < 3.20.

# Aborted by a custom log handler (a similar effect as G_DEBUG=fatal-criticals)
#0  0x00007f7592dda067 in __GI_raise (sig=sig@entry=6) at ../nptl/sysdeps/unix/sysv/linux/raise.c:56
#1  0x00007f7592ddb448 in __GI_abort () at abort.c:89
#2  0x00007f75339c3bd0 in diorite_logger_log_handler (message=0x7f7595e7aca0 "g_object_unref: assertion 'object->ref_count > 0' failed", level=<optimized out>, domain=<optimized out>) at src/glib/logger.c:510
#3  _diorite_logger_log_handler_glog_func (log_domain=log_domain@entry=0x7f75902fc856 "GLib-GObject", log_levels=log_levels@entry=G_LOG_LEVEL_CRITICAL, 
    message=message@entry=0x7f7595e7aca0 "g_object_unref: assertion 'object->ref_count > 0' failed", self=self@entry=0x0) at src/glib/logger.c:135
#4  0x00007f7590003d01 in g_logv (log_domain=0x7f75902fc856 "GLib-GObject", log_level=G_LOG_LEVEL_CRITICAL, format=<optimized out>, args=args@entry=0x7ffdd3171af0) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmessages.c:1020
#5  0x00007f7590003f6f in g_log (log_domain=<optimized out>, log_level=<optimized out>, format=<optimized out>) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmessages.c:1079
#6  0x00007f75902ec494 in g_signal_emit_valist (instance=<optimized out>, signal_id=<optimized out>, detail=<optimized out>, var_args=var_args@entry=0x7ffdd3171d20) at /build/glib2.0-y6934K/glib2.0-2.42.1/./gobject/gsignal.c:3268
#7  0x00007f75902ec9df in g_signal_emit (instance=instance@entry=0x7f7595999270, signal_id=<optimized out>, detail=detail@entry=0) at /build/glib2.0-y6934K/glib2.0-2.42.1/./gobject/gsignal.c:3365
#8  0x00007f759177ab06 in gtk_style_context_do_invalidate (context=0x7f7595999270, changes=0x7f7595dc77e0) at /tmp/buildd/gtk+3.0-3.14.5/./gtk/gtkstylecontext.c:2916
#9  0x00007f759177cf80 in gtk_style_context_invalidate (context=0x7f7595999270) at /tmp/buildd/gtk+3.0-3.14.5/./gtk/gtkstylecontext.c:3170
#10 0x00007f759177e3ac in gtk_style_context_finalize (object=0x7f7595999270) at /tmp/buildd/gtk+3.0-3.14.5/./gtk/gtkstylecontext.c:621
#11 0x00007f75902d726a in g_object_unref (_object=0x7f7595999270) at /build/glib2.0-y6934K/glib2.0-2.42.1/./gobject/gobject.c:3170
#12 0x00007f7594ba362d in derefGPtr<_GtkStyleContext> () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WTF/wtf/glib/GRefPtr.h:251
#13 ~GRefPtr () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WTF/wtf/glib/GRefPtr.h:77
#14 paint () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebCore/platform/gtk/ScrollbarThemeGtk.cpp:799
#15 0x00007f75940946bb in paint () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebCore/platform/Scrollbar.cpp:170
#16 0x00007f7594008eb9 in paintScrollbar () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebCore/page/FrameView.cpp:3790
#17 0x00007f759408e60d in paintScrollbars () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebCore/platform/ScrollView.cpp:1182
#18 0x00007f7594090a03 in paint () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebCore/platform/ScrollView.cpp:1252
#19 0x00007f75937e264c in drawRect () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/WebProcess/WebPage/WebPage.cpp:1359
#20 0x00007f75938ad339 in display () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/WebProcess/WebPage/DrawingAreaImpl.cpp:679
#21 0x00007f75938aea22 in display () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/WebProcess/WebPage/DrawingAreaImpl.cpp:590
#22 0x00007f75938e21ea in callMemberFunctionImpl<WebKit::DrawingArea, void (WebKit::DrawingArea::*)(), std::tuple<> > () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/HandleMessage.h:16
#23 callMemberFunction<WebKit::DrawingArea, void (WebKit::DrawingArea::*)(), std::tuple<>, std::make_index_sequence<0ul> > () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/HandleMessage.h:22
#24 handleMessage<Messages::DrawingArea::DidUpdate, WebKit::DrawingArea, void (WebKit::DrawingArea::*)()> () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/HandleMessage.h:92
#25 didReceiveMessage () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/obj-x86_64-linux-gnu/DerivedSources/WebKit2/DrawingAreaMessageReceiver.cpp:62
#26 0x00007f7593649a53 in dispatchMessage () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/MessageReceiverMap.cpp:102
#27 0x00007f7593759216 in didReceiveMessage () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/WebProcess/WebProcess.cpp:580
#28 0x00007f7593645b46 in dispatchMessage () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/Connection.cpp:922
#29 0x00007f75936464b0 in dispatchOneMessage () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WebKit2/Platform/IPC/Connection.cpp:953
#30 0x00007f7592bb30d9 in performWork () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WTF/wtf/RunLoop.cpp:105
#31 0x00007f7592bd6e39 in operator() () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WTF/wtf/glib/RunLoopGLib.cpp:66
#32 _FUN () at /home/fenryxo/dev/upstream/pkg-webkit/pkg-webkit/Source/WTF/wtf/glib/RunLoopGLib.cpp:68
#33 0x00007f758fffcb6d in g_main_dispatch (context=0x7f75959aaee0) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmain.c:3111
#34 g_main_context_dispatch (context=context@entry=0x7f75959aaee0) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmain.c:3710
#35 0x00007f758fffcf48 in g_main_context_iterate (context=0x7f75959aaee0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmain.c:3781
#36 0x00007f758fffd272 in g_main_loop_run (loop=0x7f7595fcbe80) at /build/glib2.0-y6934K/glib2.0-2.42.1/./glib/gmain.c:3975

[Carlos Garcia Campos]

This reminds me a gtk bug that was fixed in gtk long time ago, maybe you need to backport it. I'll try to find it.

[Carlos Garcia Campos]

hmm, I'm not sure but it could be this one, https://bugzilla.gnome.org/show_bug.cgi?id=709491. Could you try that patch?

[Jiří Janoušek]

I'm sorry but I don't have time to test that GTK+ patch. Also, I'm no longer interested in this bug as I now use Flatpak builds to provide my users with the latest stable WebKitGTK & GTK+ releases. You can close this ticket if you wish.

[Michael Catanzaro]

OK then.