title: What could cause this crash on the libdispatch-manager thread?
body: <pre><code>Date/Time: 2013-05-22 21:31:31.863 -0400  
  OS Version: iOS 6.1.3 (10B329)  
  Report Version: 104  
  
  Exception Type: EXC_CRASH (SIGSEGV)  
  Exception Codes: 0x0000000000000000, 0x0000000000000000  
  Crashed Thread: 1  
  
  Thread 0 name: Dispatch queue: com.apple.main-thread  
  Thread 0:  
  0 CoreFoundation 0x3203f950 -[NSArrayM dealloc] + 128    
  1 Foundation 0x32999218 -[NSFunctionExpression dealloc] + 56  
  2 Foundation 0x329991d8 -[NSKeyPathExpression dealloc] + 36  
  3 Foundation 0x3299914c -[NSComparisonPredicate dealloc] + 40  
  4 CoreData 0x31f6b672 -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:] + 1362  
  5 CoreFoundation 0x32045034 _CFXNotificationPost + 1424  
  6 Foundation 0x3295b594 -[NSNotificationCenter postNotificationName:object:userInfo:] + 68  
  7 CoreData 0x31ef9712 -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:] + 74  
  8 CoreData 0x31ef8c72 -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:] + 294  9 CoreData 0x31e7abf4 - [NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:] + 2676  
  10 CoreData 0x31e7a10a _performRunLoopAction + 266  
  11 CoreFoundation 0x320c96ca __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION + 18  
  12 CoreFoundation 0x320c79bc __CFRunLoopDoObservers + 272  
  13 CoreFoundation 0x320c7d12 __CFRunLoopRun + 738  
  14 CoreFoundation 0x3203aeb8 CFRunLoopRunSpecific + 352  
  15 CoreFoundation 0x3203ad44 CFRunLoopRunInMode + 100    
  16 GraphicsServices 0x35bef2e6 GSEventRunModal + 70  
  17 UIKit 0x33f502fc UIApplicationMain + 1116  
  18 MyApp 0x00003fd6 main (main.m:16)  
  19 MyApp 0x00003f8c 0x1000 + 12172  
  
  Thread 1 name: Dispatch queue: com.apple.libdispatch-manager  
  Thread 1 Crashed:  
  0 libsystem_kernel.dylib 0x3a486648 kevent64 + 24  
  1 libdispatch.dylib 0x3a3b6974 _dispatch_mgr_invoke + 792  
  2 libdispatch.dylib 0x3a3b6654 _dispatch_mgr_thread$VARIANT$mp + 32  
  </code></pre>