App hangs on card-scanning screen

[ABorshche]

App hangs on card-scanning screen when going back to foreground and keeps hanging up to 1 minute. And some times app even get killed by system.

Steps:

1. Launch SampleApp or SampleApp-Swift
2. Navigate to the card-scanning screen.
3. Tap the iPhone's Home button to background the app.
4. Double-tap the Home button and return app.

Reproduces every time on my iPhone 5s iOS 9.0.2

[bluk]

@ABorshche are you able to reproduce this on other devices? Also, which version of card.io are you using?

I don't have an iPhone 5s with exactly iOS 9.0.2 immediately on hand but tried a couple other devices including an iPhone 5 with iOS 8.4. I wasn't able to reproduce the issue with the freezing.

[ABorshche]

I tried several devices with iOS 8/9 and also wasn't able to reproduce the issue. But is 100% reproduces on all 3 of iPhone 5s with iOS 9.0.2 which i have. So looks like it is device/OS specific issue. Unfortunately i have no iPhone 5s with any other iOS version.

I used CardIO 5.2.1 (SampleApp obj-c/swift form this repo).

[bluk]

@ABorshche thanks for the additional information! We will try looking as time permits but it is odd that it is only on an iPhone 5s.

[josharian]

If you kill the app while it is hung, what is the backtrack? Is it always the same?

[ABorshche]

@josharian , yes it is always the same

Incident Identifier: 6FB2FF1A-B8DB-49A6-A20C-87E972DA66FE
CrashReporter Key:   1f7f4ceffca8990ad9c893f951df1bb6be341051
Hardware Model:      iPhone6,1
Process:             ScanExample [4559]
Path:                /var/mobile/Containers/Bundle/Application/D8959B15-0316-4BD6-987E-32A502CD8C54/ScanExample.app/ScanExample
Identifier:          org.my.ScanExample
Version:             1.0 (1.0)
Code Type:           ARM-64 (Native)
Parent Process:      launchd [1]

Date/Time:           2015-10-21 10:23:07.07 +0300
Launch Time:         2015-10-21 10:22:51.51 +0300
OS Version:          iOS 9.0.2 (13A452)
Report Version:      105

Exception Type:  00000020
Exception Codes: 0x000000008badf00d
Exception Note:  SIMULATED (this is NOT a crash)
Highlighted by Thread:  0

Application Specific Information:
org.my.ScanExample failed to scene-update after 10.00s

Elapsed total CPU time (seconds): 11.090 (user 11.090, system 0.000), 55% CPU 
Elapsed application CPU time (seconds): 0.002, 0% CPU

Filtered syslog:
None found

Thread 0 name:  Dispatch queue: CompilerConnectionSerialQueue
Thread 0:
0   libsystem_kernel.dylib          0x0000000197dacc6c semaphore_wait_trap + 8
1   libdispatch.dylib               0x0000000197c8a684 _dispatch_semaphore_wait_slow + 244
2   libxpc.dylib                    0x0000000197ec29f8 xpc_connection_send_message_with_reply_sync + 204
3   AGXCompilerConnection           0x000000018920640c 0x189204000 + 9228
4   libdispatch.dylib               0x0000000197c79770 _dispatch_client_callout + 16
5   libdispatch.dylib               0x0000000197c849c4 _dispatch_barrier_sync_f_invoke + 100
6   AGXCompilerConnection           0x00000001892062f4 XPCCompilerConnection::BuildRequest(NSObject<OS_dispatch_data>*, NSObject<OS_dispatch_data>*, void (void const*, unsigned long) block_pointer) + 116
7   AGXGLDriver                     0x0000000180d827b0 AGXHalShaderFactoryT<AGXUserVertexShaderKey, AGXHalVertexShader>::create(AGXUserVertexShaderKey const*) + 204
8   AGXGLDriver                     0x0000000180db5b14 AGXVertexShader::getCompiledVariant(AGXContextRec*, _AGCVertexContextStateGL const*, _AGCSamplerPCFStates const*, unsigned int&) + 352
9   AGXGLDriver                     0x0000000180db6750 glrUpdateCtxSysVertexProgram + 292
10  AGXGLDriver                     0x0000000180d4511c gpusLoadCurrentPipelinePrograms + 588
11  AGXGLDriver                     0x0000000180d71d28 gldUpdateDispatch + 1336
12  GLEngine                        0x0000000185e33860 gleDoDrawDispatchCoreES2 + 632
13  GLEngine                        0x0000000185e0a570 gleDrawArraysOrElements_Entries_Body + 180
14  GLEngine                        0x0000000185e08ab0 glDrawElements_ES2Exec + 204
15  ScanExample                     0x000000010004ff54 -[CardIOGPURenderer withContextDo:] + 208
16  ScanExample                     0x000000010005069c -[CardIOGPURenderer renderToSize:] + 100
17  ScanExample                     0x000000010004ff54 -[CardIOGPURenderer withContextDo:] + 208
18  ScanExample                     0x0000000100050c00 -[CardIOGPURenderer renderUIImage:toSize:] + 148
19  ScanExample                     0x000000010004f7cc -[CardIOGPUFilter processUIImage:toSize:] + 52
20  ScanExample                     0x0000000100053688 __53-[CardIOGPUGaussianBlurFilter processUIImage:toSize:]_block_invoke + 116
21  ScanExample                     0x000000010004ff54 -[CardIOGPURenderer withContextDo:] + 208
22  ScanExample                     0x000000010005358c -[CardIOGPUGaussianBlurFilter processUIImage:toSize:] + 212
23  ScanExample                     0x00000001000363a4 +[CardIOUtilities blurredScreenImageView] + 356
24  ScanExample                     0x0000000100018bac -[CardIOPaymentViewController didReceiveBackgroundingNotification:] + 108
25  CoreFoundation                  0x000000018291e6ac __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20
26  CoreFoundation                  0x000000018291decc _CFXRegistrationPost + 396
27  CoreFoundation                  0x000000018291dc4c ___CFXNotificationPost_block_invoke + 60
28  CoreFoundation                  0x0000000182983434 -[_CFXNotificationRegistrar find:object:observer:enumerator:] + 1532
29  CoreFoundation                  0x000000018285e834 _CFXNotificationPost + 368
30  Foundation                      0x00000001837ca2fc -[NSNotificationCenter postNotificationName:object:userInfo:] + 68
31  UIKit                           0x0000000187f38f3c -[UIApplication _deactivateForReason:notify:] + 800
32  UIKit                           0x000000018816de70 __61-[UIApplication _sceneSettingsPreLifecycleEventDiffInspector]_block_invoke + 124
33  FrontBoardServices              0x000000018c6b0b90 __52-[FBSSettingsDiffInspector inspectDiff:withContext:]_block_invoke27 + 208
34  Foundation                      0x00000001838795b8 __NSIndexSetEnumerate + 716
35  BaseBoard                       0x0000000189dc2898 -[BSSettingsDiff inspectChangesWithBlock:] + 104
36  FrontBoardServices              0x000000018c6abbe0 -[FBSSettingsDiff inspectOtherChangesWithBlock:] + 88
37  FrontBoardServices              0x000000018c6b0968 -[FBSSettingsDiffInspector inspectDiff:withContext:] + 292
38  UIKit                           0x000000018816f288 __70-[UIApplication scene:didUpdateWithDiff:transitionContext:completion:]_block_invoke + 120
39  UIKit                           0x000000018816ef30 -[UIApplication scene:didUpdateWithDiff:transitionContext:completion:] + 708
40  FrontBoardServices              0x000000018c6bf7ec -[FBSSerialQueue _performNext] + 184
41  FrontBoardServices              0x000000018c6bfb6c -[FBSSerialQueue _performNextFromRunLoopSource] + 56
42  CoreFoundation                  0x00000001829305a4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 24
43  CoreFoundation                  0x0000000182930038 __CFRunLoopDoSources0 + 540
44  CoreFoundation                  0x000000018292dd38 __CFRunLoopRun + 724
45  CoreFoundation                  0x000000018285cdc0 CFRunLoopRunSpecific + 384
46  GraphicsServices                0x000000018d9b0088 GSEventRunModal + 180
47  UIKit                           0x0000000187f36f44 UIApplicationMain + 204
48  ScanExample                     0x0000000100016fcc main (main.m:15)
49  libdyld.dylib                   0x0000000197caa8b8 start + 4

Thread 1 name:  Dispatch queue: com.apple.libdispatch-manager
Thread 1:
0   libsystem_kernel.dylib          0x0000000197dc859c kevent_qos + 8
1   libdispatch.dylib               0x0000000197c8ca04 _dispatch_mgr_invoke + 232
2   libdispatch.dylib               0x0000000197c7b93c _dispatch_source_invoke + 0

[dgoldman-pdx]

Looks like upon backgrounding, the code that creates a blurred screenshot (for the app snapshot that appears in the app-switcher) failed to run to completion. Probably a timeout?

I do have simpler code lying around somewhere for screen-blurring (*). Maybe updating that method would help.

(*) which this margin is too narrow to contain

[ABorshche]

@dgoldman-ebay, disableBlurWhenBackgrounding flag indeed solves the issue for 5s.

[dgoldman-pdx]

@ABorshche that's reassuring!

@bluk I'll try to find a free moment to send you a pull request in https://github.com/card-io/card.io-iOS-source with the improved screen-blurring code.

[bluk]

Thanks to @dgoldman-ebay's fix which is in release 5.2.2.