iOS app sometimes crashes in background

[cyBerta]

The crash happens in the core as we can see in the crash log.

Nevertheless ChatViewController.startTimer() should be stopped when the app is in background / the display is turned off because the closure in startTimer() is responsible for updating the UI. That's not needed at all in this situation.

Hardware Model:      iPhone13,3
Process:             deltachat-ios [5128]
Path:              
Identifier:          chat.delta
Version:             49 (1.16.0)
AppStoreTools:       12D4d
AppVariant:          1:iPhone13,3:14
Beta:                YES
Code Type:           ARM-64 (Native)
Role:                unknown
Parent Process:      launchd [1]
Coalition:           chat.delta [1283]


Date/Time:           2021-02-13 14:42:13.5452 +0100
Launch Time:         2021-02-13 10:38:01.0939 +0100
OS Version:          iPhone OS 14.4 (18D52)
Release Type:        User
Baseband Version:    1.42.03
Report Version:      104

Exception Type:  EXC_CRASH (SIGKILL)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note:  EXC_CORPSE_NOTIFY
Termination Reason: Namespace RUNNINGBOARD, Code 0xdead10cc
Triggered by Thread:  0

Thread 0 name:
Thread 0 Crashed:
0   libsystem_kernel.dylib        	0x00000001be6b4ac8 pread + 8
1   DcCore                        	0x00000001013e4a20 0x100af4000 + 9374240
2   DcCore                        	0x00000001013f275c 0x100af4000 + 9430876
3   DcCore                        	0x00000001013f2460 0x100af4000 + 9430112
4   DcCore                        	0x0000000101416e0c 0x100af4000 + 9580044
5   DcCore                        	0x0000000101411d4c 0x100af4000 + 9559372
6   DcCore                        	0x0000000101418bc8 0x100af4000 + 9587656
7   DcCore                        	0x00000001014035d4 0x100af4000 + 9500116
8   DcCore                        	0x00000001013cf848 0x100af4000 + 9287752
9   DcCore                        	0x0000000101343cb8 0x100af4000 + 8715448
10  DcCore                        	0x00000001010302e0 0x100af4000 + 5489376
11  DcCore                        	0x0000000100bdb374 0x100af4000 + 947060
12  DcCore                        	0x0000000100b8026c 0x100af4000 + 574060
13  DcCore                        	0x0000000100f17840 0x100af4000 + 4339776
14  DcCore                        	0x0000000101095c44 0x100af4000 + 5905476
15  DcCore                        	0x0000000100b008c8 DcContext.getChatMessages(chatId:) + 52 (Wrapper.swift:253)
16  DcCore                        	0x0000000100b008c8 DcContext.getMessageIds(chatId:count:from:) + 72 (Wrapper.swift:31)
17  deltachat-ios                 	0x0000000100477f10 ChatViewController.getMessageIds() + 64 (ChatViewController.swift:746)
18  deltachat-ios                 	0x0000000100477f10 closure #1 in closure #1 in ChatViewController.startTimer() + 124 (ChatViewController.swift:294)
19  deltachat-ios                 	0x0000000100517318 thunk for @escaping @callee_guaranteed () -> () + 20 (<compiler-generated>:0)
20  libdispatch.dylib             	0x000000019035024c _dispatch_call_block_and_release + 32 (init.c:1454)
21  libdispatch.dylib             	0x0000000190351db0 _dispatch_client_callout + 20 (object.m:559)
22  libdispatch.dylib             	0x000000019035f7ac _dispatch_main_queue_callback_4CF + 836 (inline_internal.h:2548)
23  CoreFoundation                	0x00000001906d911c __CFRUNLOOP_IS_SERVICING_THE_MAIN_DISPATCH_QUEUE__ + 16 (CFRunLoop.c:1790)
24  CoreFoundation                	0x00000001906d3120 __CFRunLoopRun + 2508 (CFRunLoop.c:3118)
25  CoreFoundation                	0x00000001906d221c CFRunLoopRunSpecific + 600 (CFRunLoop.c:3242)
26  GraphicsServices              	0x00000001a829e784 GSEventRunModal + 164 (GSEvent.c:2259)
27  UIKitCore                     	0x0000000193112ee8 -[UIApplication _run] + 1072 (UIApplication.m:3253)
28  UIKitCore                     	0x000000019311875c UIApplicationMain + 168 (UIApplication.m:4707)
29  deltachat-ios                 	0x000000010046494c main + 68 (AppDelegate.swift:12)
30  libdyld.dylib                 	0x00000001903926b0 start + 4

[cyBerta]

@dignifiedquire did I recall correctly this bug happens if the app is in background?

[cyBerta]

Reminder to myself: check if it's possible to upload symbols with each iOS app release so that crash logs in the core are easier to read

[dignifiedquire]

yes this happens usually when the app is in the background

[cyBerta]

DcContext.getChatMessages(chatId:) calls dc_get_chat_msgs

[link2xt]

Since it's a SIGKILL, it's not even a panic/unwrap, which normally results in SIGABRT.

Here is a similar issue I found:
https://github.com/Adobe-Marketing-Cloud/mobile-services/issues/352

[jum]

It may be that you simply use too much undeclared time in your background processing. If you wrap your background processing with UIApplictaion.beginBackgroundTask/EndBackgroundTask you get more time allocated before iOS starts KILLing you.

[cyBerta]

If you wrap your background processing with UIApplictaion.beginBackgroundTask/EndBackgroundTask

We're already doing that. Anyways, I hope this will be fixed by stopping the timer if the UI is not visible anymore.