Crashes in __CFTSDFinalize

Question

we have a serious crashing bug we can absolutely not get a hold of. The problem is that it happens to happen asynchronously in the background, obviously when the dispatch system cleans up a worker thread. Here are two example stack traces:

Thread 7 Crashed:
0   libobjc.A.dylib                     0x3b23b5b0 objc_msgSend + 15
1   Foundation                          0x33c03581 -[NSNotificationCenter postNotificationName:object:userInfo:] + 49
2   Foundation                          0x33cb3367 __NSFinalizeThreadData + 255
3   CoreFoundation                      0x3336cf81 __CFTSDFinalize + 65
4   libsystem_c.dylib                   0x3b68a12b _pthread_tsd_cleanup + 174
5   libsystem_c.dylib                   0x3b689e03 _pthread_exit + 119
6   libsystem_c.dylib                   0x3b68cd02 _pthread_workq_return + 26
7   libsystem_c.dylib                   0x3b68ca16 _pthread_wqthread + 366

And:

Thread 8 Crashed:
0   Foundation                          0x31bfd2e2 __NSFinalizeThreadData + 122
1   CoreFoundation                      0x312b6f81 __CFTSDFinalize + 65
2   libsystem_c.dylib                   0x395d412b _pthread_tsd_cleanup + 174
3   libsystem_c.dylib                   0x395d3e03 _pthread_exit + 119
4   libsystem_c.dylib                   0x395d6d02 _pthread_workq_return + 26
5   libsystem_c.dylib                   0x395d6a16 _pthread_wqthread + 366

All these crash reports seem to have the same reason:

Exception Type:  SIGSEGV
Exception Codes: SEGV_ACCERR at 0x9209ea83

I got as far as this: It seems there is an NSThreadWillExitNotification being posted. Crash logs occur more often without the NSNotificationCenter frame (second example). Regular invocations just pass @"NSThreadWillExitNotification", the NSThread object, nil userInfo.

All problems I can think of right now is the NSThread object being overreleased somehow. I just checked and all uses we make of NSThread are simple equivalence checks with the main thread. Like so:

if (NSThread.currentThread == NSThread.mainThread) ...

Any insights? Just another weird ARC issue?

Thank you all,
Max

Related, perhaps? http://stackoverflow.com/questions/12901031/segv-accerr-calling-nsnotificationcenter-defaultcenter-removeobserverself-i — CodaFi, Apr 12 '13 at 16:14
@CodaFi Not really, because this method happens to be called after all user-objects have been freed. — Max Seelemann, Apr 12 '13 at 16:16
Solved this already? I have the same problem with my project — Robin van Dijke, Aug 16 '13 at 11:17
Try running your application in Instruments using the Zombies template or the Allocations template. This looks like a run of the mill object-accessed-after-being-freed problem to me. — ipmcc, Aug 19 '13 at 12:29

score 0 · Accepted Answer · answered Dec 06 '13 at 16:35

0

A mysterious as it was, the issue seems to have vanished since iOS 7. It has also vanished since compiling with Xcode 4.6.3. So either (or both) of these seems to have fixed the bug.

answered Dec 06 '13 at 16:35

Max Seelemann

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Crashes in __CFTSDFinalize

1 Answers1