random crash on win32 export (imgui?)

pie · April 2023

This is almost certainly related to imgui, because the same error leading to crash happens randomly on giderosplayer: however exporting my app to win32 show another couple of lines of error that might help to understand what happens.

GL_VERSION:4.6.0 - Build 27.20.100.9365
 
GLSL_VERSION:4.60 - Build 27.20.100.9365
 
*visit(EnterFrameEvent* v)* stack NOT ok begin:0 end:3 delta:0
*CppLuaBridge::luaEvent* stack NOT ok begin:0 end:3 delta:0
*enterFrame* stack NOT ok begin:0 end:3 delta:0
[6815] ../Common/imgui_src/imgui.cpp: font && font->IsLoaded()  --this is the usual error I get on random crash in gideros player, but I only get this line.
stack traceback:
        [string "dialogs.lua"]:490: in function drawGUI  -- line 490 content is UI:newFrame(e.deltaTime)

MoKaLux · April 2023

I had the exact same error https://forum.gideros.rocks/discussion/comment/67992/#Comment_67992
First I was using imgui and I thought that was the issue so I removed imgui from my app to use custom made buttons.
But the error persisted so imgui was not the cause

After some more research it turned out to be an issue with my path name:
- "gfx/adventurer-Sheet.png" -- error on win32 export
- "gfx\\adventurer-Sheet.png" -- error solved

So make sure ALL your paths are using \\ for win32.

pie · April 2023

Thank you @MoKaLux you might be right, because on one app I've built the error seems to have disappeared, on the other one (which is a tool app built on imgui dialogs example it persists). I still have to investigate it further, maybe the way dialogs write paths is "wrong"?.

What I don't understand is why this happens random: I suppose that if it could not read paths it CAN NOT read them at all, not that sometimes it can, and sometimes can't, based on some planet alignment..

MoKaLux · April 2023

To be more precise about my case exporting to win32:
- using imgui my app didn't crash at all I had the message *visit(EnterFrameEvent* v)* stack NOT ok begin:0 end:3 delta:0... in the win32 console
- after replacing imgui with my button class, the app crashed immediatly on launch AND the fix was to replace / with \\ for an image (I will try to reproduce it)
- the "faulty" line was located in EnterFrame

Maybe it has something to do with threading, for example in Qt export I could just call openFileDialog but in win32 export I have to call openFileDialog via asyncCall? ImGui may handle threading like Qt thus the random crashes on win32 export.

hgy29 · April 2023

The problem looks like a memory management/pointer issue. It really can't be caused by / or \ in paths since the file access would fail immediately in that case. So maybe imgui, maybe other plugins, and even maybe threading issues or platform dependant. If we could reproduce, then it could be spotted with a debugger.

MoKaLux · April 2023

hgy29 said:
The problem looks like a memory management/pointer issue. It really can't be caused by / or \ in paths since the file access would fail immediately in that case....

I can confirm because I cannot seem to reproduce the error switching \\ to /

	if self:isValidTexture(g_Ycurrentpath) then
--		print(g_Ycurrentpath)
	else g_Ycurrentpath = "gfx/adventurer-Sheet.png" -- for Qt
--	else g_Ycurrentpath = "gfx\\adventurer-Sheet.png" -- for win32
	end
	if g_Ycurrentpath == "gfx/adventurer-Sheet.png" then -- for Qt
--	if g_Ycurrentpath == "gfx\\adventurer-Sheet.png" then -- for win32
		self.isdemo = true
		print("isdemo", self.isdemo)
	end

While thinking about how // "seemed" to have fixed my problem I was using json.encode/decode (https://wiki.gideros.rocks/index.php/Examples#JSON_V2_.40mokalux) to write/read data from a text file (file_path, bg_color, ...).

@pie are you using json too?

EDIT: I cannot reproduce the bug at all when reverting to \ on win32

pie · April 2023

@hgy29 since I have an app that often presents the issue can I somehow run it in debug mode to have more output to help understanding what happens?
It seems so far that the crash happens only on windows (gideros player, win32 and Qt export) though.

thank you

hgy29 · April 2023

@pie, yes, but you'll need to run it with debug symbols. Easiest path would be to set up Gideros player build on your computer, and run your project in debug mode with QT creator.

If someone have a demo project that exhibits the issue, I can also try to debug it myself!

hgy29 · April 2023

@pie, thanks for your help, the demo project you sent me did crash at every run under the debugger, which allowed me to find the issue (in theb font atlas loader). Here is a fixed .dll for windows qt: https://hieroglyphe.net/gideros/imgui.zip

pie · April 2023

Thank you @hgy29!! you really are a master

I'm sorry I have one more question about this.
We have various imgui.dll in gideros folder: does this replace only the one in
\Templates\Qt\windowsdesktopTemplate\plugin
or could this be used to replace also the one that is used by gideros desktop player?
(I am not sure if it is the one in \Plugins or the one inside\All Plugins\imgui\bin -the file size seems to be the same).

I guess that for win32 we will have to wait for the next gideros release and it's totally fine.

I've never experienced the same crash on android yet, given that now you know what was the cause: do you think there is a chance it might happen there too?

thank you again

hgy29 · April 2023

Yes, the dll will be the same for player (directly under plugins folder of gideros installation folder). I can build it for win32 too if you want.

And yes, the bug is platform independent, and could happen on android too

pie · April 2023

Thank you very much, personally I can wait for win32 until next full gideros release, but if you have the time to do it I would ask you to build it for android since I am publishing an app there in these days, and it is already out for internal testers

hgy29 · April 2023

@pie: https://hieroglyphe.net/gideros/imgui-Android.zip

pie · April 2023

hgy29 said:
@pie: https://hieroglyphe.net/gideros/imgui-Android.zip

WONDERFUL! Thank you.

Shall I just overwrite Gideros\All Plugins\imgui\bin\Android\ with the content of your file?

hgy29 · April 2023

yes, exactly

rrraptor · May 2023

@hgy29
This is the fix?
https://github.com/gideros/gideros/blob/881c45e282586ca28a5740d82ad1cf9d9a97b907/plugins/imgui/source/Common/imgui_bindings.cpp#L10437

Mem leak: we should delete ranges above at some point, but when ? ImGui expects it to be live as long as the font is used

Just use smart pointers?

hgy29 · May 2023

Yes. This is the fix. C pointers aren’t smart, the best we can do is delete them at some point we are sure don’t atlas or the whole imgui instance is no longer used.

rrraptor · May 2023

ImGui expects it to be live as long as the font is used

Where did you find this information? I cant see anything like this in FAQ: https://github.com/ocornut/imgui/blob/master/docs/FONTS.md

From what I can tell, imgui copies configuration (including "ranges->Data" I guess?) to its own persistent storage here:
https://github.com/ocornut/imgui/blob/70cca1eac07aa3809bdd3717253c3754a5b7cfcc/imgui_draw.cpp#L2079
So, we can safely delete our "ranges" object?

hgy29 · May 2023

See here: https://github.com/ocornut/imgui/blob/70cca1eac07aa3809bdd3717253c3754a5b7cfcc/imgui.h#L2794

hgy29 · May 2023

Seems like it can be freed after build thoug

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