Crash on iPad mini with SKGLView

[entdark]

I got a few crash reports about crashes on iPad mini (A1455) and iPad mini 2 (Wi-Fi).
Example of a crash report on iPad mini 2 (Wi-Fi):

Incident Identifier: 44FF5E1A-B0B9-4052-8630-A0E05E4E7857
CrashReporter Key: AF3F796B-1B6B-46D9-B83B-365BF3405414
Hardware Model: iPad4,4
Process: [renamed process] [8979]
Path: /var/containers/Bundle/Application/A536E6F1-85DA-4908-B52C-0B59CB765790/[renamed path]
Identifier: [renamed bundle id]
Version: 1.6 (1.6)
Code Type: ARM-64
Parent Process: ??? [1]

Date/Time: 2017-11-24T18:22:20Z
Launch Time: 2017-11-24T16:45:25Z
OS Version: iPhone OS 11.1 (15B93)
Report Version: 104

Exception Type: SIGSEGV
Exception Codes: SEGV_ACCERR at 0x1
Crashed Thread: 0

Thread 0 Crashed:
0 libGPUSupportMercury.dylib 0x00000001a2091efc 0x1a2090000 + 7932
1 libGPUSupportMercury.dylib 0x00000001a2092edc 0x1a2090000 + 11996
2 AGXGLDriver 0x00000001a61c1734 0x1a619a000 + 161588
3 GLEngine 0x00000001a71ab01c 0x1a70cd000 + 909340
4 OpenGLES 0x0000000189dcea8c 0x189dc6000 + 35468
5 GLKit 0x0000000193d70988 0x193d4e000 + 141704

iPad mini (A1455) has a similar crash report, it only differs with

Code Type: ARM
OS Version: iPhone OS 9.2 (13C75)

According to googling it happens when the app uses GPU when minimized.
So I guess the OpenGL does not get flushed properly on pause event.

When I used raw OpenGL 2.0 so the OpenGLView view I used this in the main render loop and it worked fine:

if (this.Sleeping) {
	if (!this.wentSleeping) {
		this.GameView.HasRenderLoop = false;
		this.wentSleeping = true;
	}
	return;
} else if (this.wentSleeping) {
	this.wentSleeping = false;
}

But it was added because it crashed on all iOS devices.
When I have migrated to SkiaSharp the problem did not occur at all on all devices, so I thought that is handled on Skia side properly.

Used packages:
Xamarin.Forms 2.4.0.38779
SkiaSharp.Views.Forms 1.59.2

[entdark]

It also has crashed on iPad Air with iOS 11.0.3

[migueldeicaza]

Please provide a self-contained test case and reopen the issue.

[entdark]

The issue is related to this: https://developer.apple.com/library/archive/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/OpenGLESApplicationDesign/OpenGLESApplicationDesign.html#//apple_ref/doc/uid/TP40008793-CH6-SW15
"You should flush the command buffer when your app moves to the background, because executing OpenGL ES commands on the GPU while your app is in the background causes iOS to terminate your app."
Is there a way to flush the OpenGL context in SKGLView before minimizing on iOS @mattleibow?
If no, could such a feature be added?

[mattleibow]

I think I see what might be happening. Chances are the render loop is still running.
I am assuming Xamarin.Forms here?

The best option would be to disable the render loop when disappearing and then re-enable on appearing - even if I do any magic here. This way you have full control. But, I think this may actually an issue on other platforms.

I will investigate.

[entdark]

Yes, Xamarin.Forms.
Do you mean just settings HasRenderLoop = false before minimizing will call glFlush?