Crash in `backupCache` (SwiftSDK 2.4.1)

[bvirlet]

We're using the SwiftSDK 2.4.1 in production and are seeing the following crash:

Originally posted by @bvirlet in #187 (comment)

Here is the full stacktrace:

OS Version: iOS 17.6.1 (21G93)
Report Version: 104

Exception Type: EXC_BREAKPOINT (SIGTRAP)
Exception Codes: 0 at 0x00000001a61cc148
Crashed Thread: 3

Application Specific Information:
Exception 6, Code 1, Subcode 7081869640

Thread 3 Crashed:
0   libdispatch.dylib               0x3362bf148         _dispatch_sync_f
1   GeniusScanFramework             0x101953544         [inlined] SignalCache.backupCache (SignalCache.swift:70)
2   GeniusScanFramework             0x101953544         closure in SignalManager.didEnterBackground (SignalManager.swift:198)
3   GeniusScanFramework             0x100e520ec         thunk for closure
4   libdispatch.dylib               0x3362b8138         _dispatch_call_block_and_release
5   libdispatch.dylib               0x3362b9dd0         _dispatch_client_callout
6   libdispatch.dylib               0x3362cba68         _dispatch_root_queue_drain
7   libdispatch.dylib               0x3362cc098         _dispatch_worker_thread2
8   libsystem_pthread.dylib         0x3dfa0c8f4         _pthread_wqthread

Thread 0
0   libsystem_kernel.dylib          0x3b7e196c8         mach_msg2_trap
1   libsystem_kernel.dylib          0x3b7e1cec4         mach_msg2_internal
2   libsystem_kernel.dylib          0x3b7e1cddc         mach_msg_overwrite
3   libsystem_kernel.dylib          0x3b7e1cc1c         mach_msg
4   CoreFoundation                  0x3264bdf58         __CFRunLoopServiceMachPort
5   CoreFoundation                  0x3264bd5fc         __CFRunLoopRun
6   CoreFoundation                  0x3264bccd4         CFRunLoopRunSpecific
7   GraphicsServices                0x3af9a91a4         GSEventRunModal
8   UIKitCore                       0x32ad78ae4         -[UIApplication _run]
9   UIKitCore                       0x32ae2cd94         UIApplicationMain
10  GeniusScan                      0x2007fc050         main (main.swift:11)
11  <unknown>                       0x1c1ac7154         <redacted>

Thread 1
0   libsystem_pthread.dylib         0x3dfa090c4         start_wqthread

Thread 2
0   libsystem_kernel.dylib          0x3b7e19450         __workq_kernreturn
1   libsystem_pthread.dylib         0x3dfa0c97c         _pthread_wqthread

Thread 3 Crashed:
0   libdispatch.dylib               0x3362bf148         _dispatch_sync_f
1   GeniusScanFramework             0x101953544         [inlined] SignalCache.backupCache (SignalCache.swift:70)
2   GeniusScanFramework             0x101953544         closure in SignalManager.didEnterBackground (SignalManager.swift:198)
3   GeniusScanFramework             0x100e520ec         thunk for closure
4   libdispatch.dylib               0x3362b8138         _dispatch_call_block_and_release
5   libdispatch.dylib               0x3362b9dd0         _dispatch_client_callout
6   libdispatch.dylib               0x3362cba68         _dispatch_root_queue_drain
7   libdispatch.dylib               0x3362cc098         _dispatch_worker_thread2
8   libsystem_pthread.dylib         0x3dfa0c8f4         _pthread_wqthread

Thread 4 name: com.apple.uikit.eventfetch-thread
0   libsystem_kernel.dylib          0x3b7e196c8         mach_msg2_trap
1   libsystem_kernel.dylib          0x3b7e1cec4         mach_msg2_internal
2   libsystem_kernel.dylib          0x3b7e1cddc         mach_msg_overwrite
3   libsystem_kernel.dylib          0x3b7e1cc1c         mach_msg
4   CoreFoundation                  0x3264bdf58         __CFRunLoopServiceMachPort
5   CoreFoundation                  0x3264bd5fc         __CFRunLoopRun
6   CoreFoundation                  0x3264bccd4         CFRunLoopRunSpecific
7   Foundation                      0x324289b58         -[NSRunLoop(NSRunLoop) runMode:beforeDate:]
8   Foundation                      0x3242899a8         -[NSRunLoop(NSRunLoop) runUntilDate:]
9   UIKitCore                       0x32ad8c818         -[UIEventFetcher threadMain]
10  Foundation                      0x3242a0424         __NSThread__start__
11  libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 5
0   libsystem_kernel.dylib          0x3b7e1f2ac         __semwait_signal
1   libsystem_c.dylib               0x33635a5ec         nanosleep
2   libsystem_c.dylib               0x3363b7728         sleep
3   GeniusScanFramework             0x1019af4e8         monitorCachedData
4   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 6 name: SentryCrash Exception Handler (Secondary)
0   libsystem_kernel.dylib          0x3b7e196c8         mach_msg2_trap
1   libsystem_kernel.dylib          0x3b7e1cec4         mach_msg2_internal
2   libsystem_kernel.dylib          0x3b7e1cddc         mach_msg_overwrite
3   libsystem_kernel.dylib          0x3b7e1cc1c         mach_msg
4   GeniusScanFramework             0x101995908         handleExceptions
5   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 8 name: io.sentry.app-hang-tracker
0   libsystem_kernel.dylib          0x3b7e1f2ac         __semwait_signal
1   libsystem_c.dylib               0x33635a5ec         nanosleep
2   Foundation                      0x3243dc2e0         +[NSThread sleepForTimeInterval:]
3   GeniusScanFramework             0x101976018         -[SentryANRTracker detectANRs]
4   Foundation                      0x3242a0424         __NSThread__start__
5   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 9
0   libsystem_pthread.dylib         0x3dfa090c4         start_wqthread

Thread 10 name: com.apple.NSURLConnectionLoader
0   libsystem_kernel.dylib          0x3b7e196c8         mach_msg2_trap
1   libsystem_kernel.dylib          0x3b7e1cec4         mach_msg2_internal
2   libsystem_kernel.dylib          0x3b7e1cddc         mach_msg_overwrite
3   libsystem_kernel.dylib          0x3b7e1cc1c         mach_msg
4   CoreFoundation                  0x3264bdf58         __CFRunLoopServiceMachPort
5   CoreFoundation                  0x3264bd5fc         __CFRunLoopRun
6   CoreFoundation                  0x3264bccd4         CFRunLoopRunSpecific
7   CFNetwork                       0x3287d3c78         _CFHostIsDomainTopLevel
8   Foundation                      0x3242a0424         __NSThread__start__
9   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 11
0   libsystem_pthread.dylib         0x3dfa090c4         start_wqthread

Thread 12
0   libsystem_kernel.dylib          0x3b7e19450         __workq_kernreturn
1   libsystem_pthread.dylib         0x3dfa0c97c         _pthread_wqthread

Thread 13 name: com.apple.CoreMotion.MotionThread
0   libsystem_kernel.dylib          0x3b7e196c8         mach_msg2_trap
1   libsystem_kernel.dylib          0x3b7e1cec4         mach_msg2_internal
2   libsystem_kernel.dylib          0x3b7e1cddc         mach_msg_overwrite
3   libsystem_kernel.dylib          0x3b7e1cc1c         mach_msg
4   CoreFoundation                  0x3264bdf58         __CFRunLoopServiceMachPort
5   CoreFoundation                  0x3264bd5fc         __CFRunLoopRun
6   CoreFoundation                  0x3264bccd4         CFRunLoopRunSpecific
7   CoreFoundation                  0x32652af00         CFRunLoopRun
8   CoreMotion                      0x33ff29e3c         <redacted>
9   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 14
0   libsystem_kernel.dylib          0x3b7e19450         __workq_kernreturn
1   libsystem_pthread.dylib         0x3dfa0c97c         _pthread_wqthread

Thread 15
0   libsystem_kernel.dylib          0x3b7e19450         __workq_kernreturn
1   libsystem_pthread.dylib         0x3dfa0c97c         _pthread_wqthread

Thread 16
0   libsystem_kernel.dylib          0x3b7e1f08c         __psynch_cvwait
1   libsystem_pthread.dylib         0x3dfa0b6e0         _pthread_cond_wait
2   JavaScriptCore                  0x353d411dc         scavenger_thread_main
3   libsystem_pthread.dylib         0x3dfa0e068         _pthread_start

Thread 3 crashed with ARM Thread State (64-bit):
    x0: 0x0000000300505280   x1: 0x00000003025166d0   x2: 0x0000000100ecf4fc   x3: 0x0000000000000010
    x4: 0x0000000000000001   x5: 0x0000000000000010   x6: 0x0000000302b54080   x7: 0x0000000000000000
    x8: 0x0000000000000000   x9: 0x0000000400000003  x10: 0x0000000200000003  x11: 0x0000000400000003
   x12: 0x0000000302918594  x13: 0x00000000001ff800  x14: 0x00000000000007fb  x15: 0x00000000d5e628d0
   x16: 0x0000000206122c60  x17: 0x0000000206122c60  x18: 0x0000000000000000  x19: 0x000000020625fb00
   x20: 0x0000000303e41080  x21: 0x000000016f832de0  x22: 0x000000020625fff0  x23: 0x000000016f832dd0
   x24: 0x00000001fec37bc8  x25: 0x0000000302b54080  x26: 0x0000000300505280  x27: 0x00000003025166d0
   x28: 0x0000000302b54080   fp: 0x000000016f832ea0   lr: 0x0000000101953548   sp: 0x000000016f832dd0
    pc: 0x00000001a61cc148 cpsr: 0x0000000080000000



EOF

• For us, the problem happened about 50 times for 50 different users over the past 30 days.
• The crash is on a background thread.
• We are not (neither have we attempted to) reproducing it.

[Jeehut]

@bvirlet Thank you for reporting this in more detail. I have one question that is very relevant when investigating this: On what OS types and versions do you see this crash on? As you reported it happened to 50 different customers, can you tell me if it also a) happened on non-iOS platforms (if your app supports any) and b) if it happened on other versions than iOS 17.6.1, especially if any iOS 18+ versions are also affected. Or did it always happen in 17.6.1 in particular?

[bvirlet]

We're only on iOS unfortunately (no macOS, tvOS, visionOS).

It's affecting all iOS versions apparently:

[Jeehut]

@bvirlet Thank you for that feedback. Possibly, @mrackwitz has already fixed your issue in #101 as the issue sounds related. You might want to try out his fork until we have had the time to investigate further and fix this officially.

[cliffordh]

Any update?

[Jeehut]

@cliffordh We're unable to understand and reproduce the issue so far and were waiting for feedback about the PR we had linked to. If you are running into a similar issue, could you please provide details about your crashes so we have more data to analyze the issue and pinpoint where it's coming from? Thanks in advance for your help.