`Exception: EXCEPTION_ACCESS_VIOLATION` with GtkNotebooks

[nHackel]

Hello,

I've managed to produce another crash and find a MWE for it.

The MWE tracks some state in a struct and can (re-)generate a GtkNotebook from its current state. When you press the button, I throw away the existing notebook and generate a new one.

Pressing the button repeatedly and/or manually invoking GC.gc() after a crashes Gtk4.

Here is the MWE:

using Gtk4

mutable struct MyPage
	page::Int64
	values::Vector{String}
	MyPage(values) = new(1, values)
end
function mywidget(page::MyPage)
	nb = GtkNotebook()
	
	# Pages
	for (i, value) in enumerate(page.values)
		entry = GtkEntry()
		entry.text = value
		signal_connect(entry, :activate) do w
			page.values[i] = entry.text
		end
		push!(nb, entry, "$i")
	end
	
	# Page Change
	nb.page = page.page - 1
	signal_connect(nb, :switch_page) do _, _, idx
		page.page = idx + 1
	end
	return nb
end

page = MyPage(["This", "is", "a", "test"])

window = GtkWindow()
box = GtkBox(:v)
push!(window, box)
btn = GtkButton("Click me!")
push!(box, btn)

container = GtkBox(:h)
push!(box, container)

signal_connect(btn, :clicked) do w
	@idle_add begin 
		empty!(container)
		push!(container, mywidget(page))
	end
end
show(window)

First I get an error with:

┌ Warning: Executing #2:
└ @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:122
xor(prev, current_task() !== g_stack)
Stacktrace:
  [1] g_siginterruptible(f::Gtk4.GLib.var"#142#144"{Ptr{Gtk4.GLib.GValue}, UInt32, Ptr{Gtk4.GLib.GValue}, Vector{Any}, var"#2#4"{MyPage}}, cb::Any)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:237
  [2] GClosureMarshal(closuref::Ptr{Nothing}, return_value::Ptr{Gtk4.GLib.GValue}, n_param_values::UInt32, param_values::Ptr{Gtk4.GLib.GValue}, invocation_hint::Ptr{Nothing}, marshal_data::Ptr{Nothing})
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:57
  [3] glib_unref
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:288 [inlined]
  [4] gc_unref
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:280 [inlined]
  [5] finalize_gc_unref(x::Gtk4.GLib.GObject)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:312
  [6] macro expansion
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:387 [inlined]
  [7] macro expansion
    @ .\lock.jl:273 [inlined]
  [8] run_delayed_finalizers()
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:384
  [9] gobject_ref(x::GtkNotebookLeaf)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:369
 [10] convert_(::Type{Gtk4.GLib.GObject}, ptr::Ptr{Gtk4.GLib.GObject}, owns::Bool)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:194
 [11] convert (repeats 2 times)
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:183 [inlined]
 [12] #78
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gvalues.jl:187 [inlined]
 [13] getindex(gv::Base.RefValue{Gtk4.GLib.GValue}, ::Type{Any})
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gvalues.jl:248
 [14] (::Gtk4.GLib.var"#142#144"{Ptr{Gtk4.GLib.GValue}, UInt32, Ptr{Gtk4.GLib.GValue}, Vector{Any}, var"#2#4"{MyPage}})()
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:60
 [15] g_siginterruptible(f::Gtk4.GLib.var"#142#144"{Ptr{Gtk4.GLib.GValue}, UInt32, Ptr{Gtk4.GLib.GValue}, Vector{Any}, var"#2#4"{MyPage}}, cb::Any)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:244
 [16] GClosureMarshal(closuref::Ptr{Nothing}, return_value::Ptr{Gtk4.GLib.GValue}, n_param_values::UInt32, param_values::Ptr{Gtk4.GLib.GValue}, invocation_hint::Ptr{Nothing}, marshal_data::Ptr{Nothing})
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:57
 [17] glib_unref
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:288 [inlined]
 [18] gc_unref
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:280 [inlined]
 [19] finalize_gc_unref(x::Gtk4.GLib.GObject)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:312
 [20] macro expansion
    @ C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:387 [inlined]
 [21] macro expansion
    @ .\lock.jl:273 [inlined]
 [22] run_delayed_finalizers()
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\gtype.jl:384
 [23] g_yield(data::UInt64)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:267
 [24] uv_dispatch(src::Ptr{Nothing}, callback::Ptr{Nothing}, data::Int64)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:363
 [25] (::Gtk4.GLib.var"#237#238")()
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\loop.jl:83
 [26] g_sigatom(f::Any)
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\signals.jl:211
 [27] glib_main()
    @ Gtk4.GLib C:\Users\...\.julia\dev\Gtk4\src\GLib\loop.jl:80

here a lot of stacktraces are interwoven probably due to me spamming the button (edited: Managed to get a clean stacktrace)

Then after a while I get:

Please submit a bug report with steps to reproduce this fault, and any error messages that follow (in their entirety). Thanks.
Exception: EXCEPTION_ACCESS_VIOLATION at 0x67f1fd48 -- signal_emit_unlocked_R at C:\Users\...\.julia\artifacts\7de578e660d4ad9f8ddbe10244cc8730d674b85c\bin\libgobject-2.0-0.dll (unknown line)
in expression starting at none:0
signal_emit_unlocked_R at C:\Users\...\.julia\artifacts\7de578e660d4ad9f8ddbe10244cc8730d674b85c\bin\libgobject-2.0-0.dll (unknown line)
signal_emit_valist_unlocked at C:\Users\...\.julia\artifacts\7de578e660d4ad9f8ddbe10244cc8730d674b85c\bin\libgobject-2.0-0.dll (unknown line)

Some context for this setting: I have a GtkListBox which I fill various widgets. On certain actions by the user, I have to exchange certain entries in the listbox. However, the only way I managed to get that work at the moment is to completely repopulate the box. For that I track my application state not directly in GtkWidgets, but instead in a struct which then can produce a widget. One of those widgets was a notebook and after repopulation garbage collection crashes the app.

[jwahlstrand]

I can reproduce on Linux. I don't have a lot of time ATM to look into it...

[nHackel]

@jwahlstrand I've managed to "stop" the error in this PR #100, but I'm not quite sure why it works or if that produces other errors. In my application at least it didnt seem to cause other crashes