Mysterious SIGKILL in iPad application running in the simulator - ios

Question

My iPad application has recently been receiving mysterious SIGKILL signals while running in the iOS Simulator. It seems to happen within 2 minutes of application launch, but not every time.
Does this backtrace indicate anything, or should I try removing things until I find the culprit?
There are some components that could be involved; one example is that I recently integrated Crashlytics. Another example is I'm using CLGeocoder to plot a location on an MKMapView, which could explain why the problem happens at some undetermined point after the launch (and why MapKit appears in one of the threads). But without clearer indication from a backtrace or a log, I'm shooting in the dark.
Xcode 4.3.2; targeting iOS 5.
* thread #1: tid = 0x1f03, 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10, stop reason = signal SIGKILL
frame #0: 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #1: 0x9c2c41f6 libsystem_kernel.dylib`mach_msg + 70
frame #2: 0x0178110a CoreFoundation`__CFRunLoopServiceMachPort + 186
frame #3: 0x016e4550 CoreFoundation`__CFRunLoopRun + 1312
frame #4: 0x016e3d84 CoreFoundation`CFRunLoopRunSpecific + 212
frame #5: 0x016e3c9b CoreFoundation`CFRunLoopRunInMode + 123
frame #6: 0x015af7d8 GraphicsServices`GSEventRunModal + 190
frame #7: 0x015af88a GraphicsServices`GSEventRun + 103
frame #8: 0x00394626 UIKit`UIApplicationMain + 1163
frame #9: 0x00001d4d Tablecloth`main + 141 at main.m:16
frame #10: 0x00001cb5 Tablecloth`start + 53
thread #3: tid = 0x2403, 0x9c2c790a libsystem_kernel.dylib`kevent + 10
frame #0: 0x9c2c790a libsystem_kernel.dylib`kevent + 10
frame #1: 0x020b9372 libdispatch.dylib`_dispatch_mgr_invoke + 918
frame #2: 0x020b7be1 libdispatch.dylib`_dispatch_mgr_thread + 53
thread #5: tid = 0x2603, 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #0: 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #1: 0x9c2c41f6 libsystem_kernel.dylib`mach_msg + 70
frame #2: 0x0178110a CoreFoundation`__CFRunLoopServiceMachPort + 186
frame #3: 0x016e45d5 CoreFoundation`__CFRunLoopRun + 1445
frame #4: 0x016e3d84 CoreFoundation`CFRunLoopRunSpecific + 212
frame #5: 0x016e3c9b CoreFoundation`CFRunLoopRunInMode + 123
frame #6: 0x03ede420 WebCore`_ZL12RunWebThreadPv + 560
frame #7: 0x93ebced9 libsystem_c.dylib`_pthread_start + 335
thread #6: tid = 0x2703, 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #0: 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #1: 0x9c2c41f6 libsystem_kernel.dylib`mach_msg + 70
frame #2: 0x0178110a CoreFoundation`__CFRunLoopServiceMachPort + 186
frame #3: 0x016e45d5 CoreFoundation`__CFRunLoopRun + 1445
frame #4: 0x016e3d84 CoreFoundation`CFRunLoopRunSpecific + 212
frame #5: 0x016e3c9b CoreFoundation`CFRunLoopRunInMode + 123
frame #6: 0x00d94e30 Foundation`+[NSURLConnection(Loader) _resourceLoadLoop:] + 398
frame #7: 0x00ca64d6 Foundation`-[NSThread main] + 76
frame #8: 0x00ca6447 Foundation`__NSThread__main__ + 1258
frame #9: 0x93ebced9 libsystem_c.dylib`_pthread_start + 335
thread #7: tid = 0x2803, 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #0: 0x9c2c4c22 libsystem_kernel.dylib`mach_msg_trap + 10
frame #1: 0x9c2c41f6 libsystem_kernel.dylib`mach_msg + 70
frame #2: 0x0178110a CoreFoundation`__CFRunLoopServiceMachPort + 186
frame #3: 0x016e45d5 CoreFoundation`__CFRunLoopRun + 1445
frame #4: 0x016e3d84 CoreFoundation`CFRunLoopRunSpecific + 212
frame #5: 0x016e3c9b CoreFoundation`CFRunLoopRunInMode + 123
frame #6: 0x0012286b MapKit`MKNormalizedPointForLayer + 30057
frame #7: 0x00ca64d6 Foundation`-[NSThread main] + 76
frame #8: 0x00ca6447 Foundation`__NSThread__main__ + 1258
frame #9: 0x93ebced9 libsystem_c.dylib`_pthread_start + 335
thread #8: tid = 0x2903, 0x9c2c6b42 libsystem_kernel.dylib`select$DARWIN_EXTSN + 10
frame #0: 0x9c2c6b42 libsystem_kernel.dylib`select$DARWIN_EXTSN + 10
frame #1: 0x017157cb CoreFoundation`__CFSocketManager + 939
frame #2: 0x93ebced9 libsystem_c.dylib`_pthread_start + 335
thread #9: tid = 0x2a03, 0x9c2c702e libsystem_kernel.dylib`__workq_kernreturn + 10
frame #0: 0x9c2c702e libsystem_kernel.dylib`__workq_kernreturn + 10
frame #1: 0x93ebeccf libsystem_c.dylib`_pthread_wqthread + 773
EDIT: The Crashlytics support team helped me debug this, and the thing that seemed to fix it was to use the "Reset Content and Settings…" menu item in the Simulator app. It's not clear why exactly this happened, but I'm not getting the debugging interruptions anymore.

Answer 1

SIGKILL generally suggests that you were killed by the OS. Your console logs are going to be more useful than the stack traces. If it were on device, I would suspect using too much memory, but that's very unlikely in the simulator. The other common SIGKILL is if you block your main thread too long, so I'd look for that (though I didn't think the simulator provided that one).
But your best place to look is in the run log.