On Ubuntu 15.10, gedit randomly (about half the time) hangs when either the Open or the Save As dialog is opened.
The cause appears to be a deadlock:
Thread 1 is in a GCancellable::cancelled signal handler, and indirectly calls g_dbus_connection_signal_subscribe which tries to acquire a GDBusConnection's mutex
Thread 3 is in on_worker_message_received, which holds the GDBusConnection's mutex and indirectly calls g_cancellable_disconnect which waits for the GCancellable's signal handler to complete.
Thread 1 (Thread 0x7ffff7f27a00 (LWP 10630)):
#0 0x00007ffff48c45a9 in syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
#1 0x00007ffff514102c in g_mutex_lock_slowpath (mutex=mutex@entry=0x6e55a8) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gthread-posix.c:1315
#2 0x00007ffff5141872 in g_mutex_lock (mutex=mutex@entry=0x6e55a8) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gthread-posix.c:1339
#3 0x00007ffff591cdb9 in g_dbus_connection_signal_subscribe (connection=0x6e5590 [GDBusConnection], sender=0x0, interface_name=interface_name@entry=0x7ffff5969d10 "org.freedesktop.DBus.Properties", member=member@entry=0x7ffff59681f0 "PropertiesChanged", object_path=0xd7a210 "/org/gtk/vfs/Daemon", arg0=0xc09880 "org.gtk.vfs.Daemon", flags=G_DBUS_SIGNAL_FLAGS_NONE, callback=0x7ffff5925da0 <on_properties_changed>, user_data=0x8be350, user_data_free_func=0x7ffff5925cf0 <signal_subscription_unref>) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusconnection.c:3445
#4 0x00007ffff59263c2 in async_initable_init_first (initable=initable@entry=0x7fffd4010780)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusproxy.c:1740
#5 0x00007ffff5927238 in async_initable_init_async (initable=0x7fffd4010780, io_priority=0, cancellable=0x0, callback=<optimized out>, user_data=<optimized out>) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusproxy.c:1862
#6 0x00007ffff587fb51 in g_async_initable_new_valist_async (object_type=<optimized out>, first_property_name=0x7fffe8c83b40 "g-flags", var_args=0x7fffffffd360, io_priority=0, cancellable=0x0, callback=0x7fffe8eb0780 <cancelled_got_proxy>, user_data=0x2)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gasyncinitable.c:426
#7 0x00007ffff587fc08 in g_async_initable_new_async (object_type=<optimized out>, io_priority=io_priority@entry=0, cancellable=cancellable@entry=0x0, callback=callback@entry=0x7fffe8eb0780 <cancelled_got_proxy>, user_data=user_data@entry=0x2, first_property_name=first_property_name@entry=0x7fffe8c83b40 "g-flags") at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gasyncinitable.c:339
#8 0x00007fffe8c74df8 in gvfs_dbus_daemon_proxy_new (connection=0x6e5590 [GDBusConnection], flags=flags@entry=G_DBUS_PROXY_FLAGS_NONE, name=name@entry=0x0, object_path=object_path@entry=0x7fffe8ebbb95 "/org/gtk/vfs/Daemon", cancellable=cancellable@entry=0x0, callback=callback@entry=0x7fffe8eb0780 <cancelled_got_proxy>, user_data=0x2) at gvfsdbus.c:1201
#9 0x00007fffe8eb0528 in async_call_cancelled_cb (cancellable=<optimized out>, _data=<optimized out>) at gvfsdaemondbus.c:376
#13 0x00007ffff53ed12f in <emit signal ??? on instance 0xd57450 [GCancellable]> (instance=instance@entry=0xd57450, signal_id=<optimized out>, detail=detail@entry=0) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gsignal.c:3439
#10 0x00007ffff53d2015 in g_closure_invoke (closure=0xd792f0, return_value=return_value@entry=0x0, n_param_values=1, param_values=param_values@entry=0x7fffffffd6b0, invocation_hint=invocation_hint@entry=0x7fffffffd630) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gclosure.c:801
#11 0x00007ffff53e4061 in signal_emit_unlocked_R (node=node@entry=0x6efa40, detail=detail@entry=0, instance=instance@entry=0xd57450, emission_return=emission_return@entry=0x0, instance_and_params=instance_and_params@entry=0x7fffffffd6b0)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gsignal.c:3627
#12 0x00007ffff53ecdfc in g_signal_emit_valist (instance=<optimized out>, signal_id=<optimized out>, detail=<optimized out>, var_args=var_args@entry=0x7fffffffd860) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gsignal.c:3383
#14 0x00007ffff58833b8 in g_cancellable_cancel (cancellable=0xd57450 [GCancellable]) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gcancellable.c:508
#15 0x00007ffff6fe6ba4 in update_places (sidebar=0xd92460 [GtkPlacesSidebar]) at /build/gtk+3.0-pIzeMy/gtk+3.0-3.16.7/./gtk/gtkplacessidebar.c:941
#16 0x00007ffff53d2244 in _g_closure_invoke_va (closure=closure@entry=0xa9c9d0, return_value=return_value@entry=0x0, instance=instance@entry=0xce7690, args=args@entry=0x7fffffffdc80, n_params=<optimized out>, param_types=0x0) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gclosure.c:864
#17 0x00007ffff53eca46 in g_signal_emit_valist (instance=0xce7690, signal_id=<optimized out>, detail=0, var_args=var_args@entry=0x7fffffffdc80)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gsignal.c:3292
#18 0x00007ffff53ed12f in g_signal_emit (instance=instance@entry=0xce7690, signal_id=<optimized out>, detail=detail@entry=0)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gobject/gsignal.c:3439
#19 0x00007ffff7097f86 in trash_enumerate_next_files_cb (has_trash=0, monitor=0xce7690 [GtkTrashMonitor])
at /build/gtk+3.0-pIzeMy/gtk+3.0-3.16.7/./gtk/gtktrashmonitor.c:102
#20 0x00007ffff7097f86 in trash_enumerate_next_files_cb (source=<optimized out>, result=<optimized out>, user_data=0xce7690)
at /build/gtk+3.0-pIzeMy/gtk+3.0-3.16.7/./gtk/gtktrashmonitor.c:124
#21 0x00007ffff5898a87 in next_async_callback_wrapper (source_object=0xe9c310 [GDaemonFileEnumerator], res=<optimized out>, user_data=<optimized out>)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gfileenumerator.c:305
#22 0x00007ffff58bda17 in g_simple_async_result_complete (simple=0xe04570 [GSimpleAsyncResult])
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gsimpleasyncresult.c:801
#23 0x00007ffff58bda79 in complete_in_idle_cb (data=<optimized out>) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gsimpleasyncresult.c:813
#24 0x00007ffff50fceaa in g_main_context_dispatch (context=0x6deea0) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3154
#25 0x00007ffff50fceaa in g_main_context_dispatch (context=context@entry=0x6deea0) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3769
#26 0x00007ffff50fd250 in g_main_context_iterate (context=context@entry=0x6deea0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3840
#27 0x00007ffff50fd2fc in g_main_context_iteration (context=0x6deea0, context@entry=0x0, may_block=may_block@entry=1)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3901
#28 0x00007ffff58f2b1c in g_application_run (application=0x6b7120 [GeditAppX11], argc=2, argv=0x7fffffffe028)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gapplication.c:2311
#29 0x00000000004231c1 in main ()
Thread 3 (Thread 0x7fffea2d6700 (LWP 10635)):
#0 0x00007ffff48c45a9 in syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38
#1 0x00007ffff51419cf in g_cond_wait (cond=cond@entry=0x7ffff5bc8110 <cancellable_cond>, mutex=mutex@entry=0x7ffff5bc8120 <cancellable_mutex>)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gthread-posix.c:1397
#2 0x00007ffff5883556 in g_cancellable_disconnect (cancellable=0xd57450 [GCancellable], handler_id=8162)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gcancellable.c:632
#3 0x00007ffff5914f4b in send_message_with_reply_cleanup (task=0xac73b0 [GTask], remove=1)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusconnection.c:1779
#4 0x00007ffff5917c32 in on_worker_message_received (reply=0xca9400 [GDBusMessage], task=0xac73b0 [GTask])
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusconnection.c:1807
#5 0x00007ffff5917c32 in on_worker_message_received (worker=<optimized out>, message=0xca9400 [GDBusMessage], user_data=0x6e5590)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusconnection.c:2283
#6 0x00007ffff592b906 in _g_dbus_worker_do_read_cb (message=0xca9400 [GDBusMessage], worker=0x7fffcc0029c0)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusprivate.c:456
#7 0x00007ffff592b906 in _g_dbus_worker_do_read_cb (message=0xca9400 [GDBusMessage], worker=0x7fffcc0029c0)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusprivate.c:484
#8 0x00007ffff592b906 in _g_dbus_worker_do_read_cb (input_stream=<optimized out>, res=<optimized out>, user_data=0x7fffcc0029c0)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusprivate.c:769
#9 0x00007ffff58ce5f3 in g_task_return_now (task=0x7fffdc0032a0 [GTask]) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gtask.c:1104
#10 0x00007ffff58ce629 in complete_in_idle_cb (task=0x7fffdc0032a0) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gtask.c:1118
#11 0x00007ffff50fceaa in g_main_context_dispatch (context=0x6f0760) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3154
#12 0x00007ffff50fceaa in g_main_context_dispatch (context=context@entry=0x6f0760) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3769
#13 0x00007ffff50fd250 in g_main_context_iterate (context=0x6f0760, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>)
at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:3840
#14 0x00007ffff50fd572 in g_main_loop_run (loop=0x6f0710) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gmain.c:4034
#15 0x00007ffff59294c6 in gdbus_shared_thread_func (user_data=0x6f0730) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./gio/gdbusprivate.c:246
#16 0x00007ffff5123965 in g_thread_proxy (data=0x6d3370) at /build/glib2.0-ajuDY6/glib2.0-2.46.1/./glib/gthread.c:778
#17 0x00007ffff4b946aa in start_thread (arg=0x7fffea2d6700) at pthread_create.c:333
#18 0x00007ffff48c9eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109
I've figured out that this bug is triggered by having bookmarked the Trash, which I must have done by accident with an errant Ctrl-D a long time ago. After removing that bookmark, the problem seems to go away. (And, just to verify, if I bookmark the Trash again, it comes back.)